Photosensitive composition, compound for use in the photosensitive composition and pattern forming method using the photosensitive composition

ABSTRACT

A photosensitive composition comprising: (A) a compound capable of generating a compound having a specific structure upon irradiation with actinic rays or radiation, a pattern forming method using the photosensitive composition, and a compound capable of generating a compound having a specific structure upon irradiation with actinic rays or radiation.

This is a continuation of application Ser. No. 11/438,728 filed May 23,2006. The entire disclosure of the prior application, application Ser.No. 11/438,728, is hereby incorporated by reference.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation of application Ser. No. 11/438,728 filed May 23,2006, which claims priority from Japanese Application No. 2005-149988filed May 23, 2005. The entire disclosures of the prior applications arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a photosensitive composition capable ofchanging its properties by undergoing a reaction upon irradiation withactinic rays or radiation, a compound for use in the photosensitivecomposition, and a pattern forming method using the photosensitivecomposition. More specifically, the present invention relates to aphotosensitive composition for use in the production process of asemiconductor such as IC, in the production of a circuit substrate ofliquid crystal, thermal head or the like, in other photofabricationprocesses or in the lithographic printing plate or acid-curablecomposition, and also relates to a compound for use in thephotosensitive composition and a pattern forming method using thephotosensitive composition.

2. Description of the Related Art

The chemical amplification resist composition is a pattern formingmaterial capable of forming a pattern on a substrate by producing anacid in the exposed area upon irradiation with radiation such as farultraviolet light and through a reaction using this acid as thecatalyst, changing the solubility in a developer between the areairradiated with actinic radiation and the non-irradiated area.

In the case of using a KrF excimer laser as the exposure light source, aresin having small absorption in the region of 248 nm and having a basicskeleton of poly(hydroxystyrene) is predominantly used as the maincomponent, and this is an excellent system capable of forming a goodpattern with high sensitivity and high resolution as compared with theconventional naphthoquinonediazide/novolak resin system.

In the case of using a light source of emitting light at a shorterwavelength, for example, in using an ArF excimer laser (193 nm) as thelight source, a satisfactory pattern cannot be formed even by theabove-described chemical amplification system because the compoundhaving an aromatic group substantially has large absorption in theregion of 193 nm.

In order to solve this problem, a resist containing a resin having analicyclic hydrocarbon structure with high transparency has beendeveloped for use with an ArF excimer laser. As for the alicyclichydrocarbon structure, a norbornene or adamantane skeleton showing hightransparency and high dry etching resistance is used as described inJP-A-2002-131897 (the term “JP-A” as used herein means an “unexaminedpublished Japanese patent application”)), JP-A-2003-149812,JP-T-11-501909 (the term (the term “JP-T” as used herein means a“published Japanese translation of a PCT patent application”),JP-A-2002-268223, JP-A-2003-246786 and JP-A-9-73173. However, thealicyclic structure generally has low polarity, and the reactivity fordeprotection in the resin is greatly decreased as compared with that inpoly(hydroxystyrene). Therefore, an acid having high acidity isnecessary for the image formation and a specific fluoro-organic sulfonicacid is used, for example, in JP-A-2002-131897 and JP-A-2003-149812.Also, a composition containing an acid generator comprising an imideanion capable of generating a high-acidity imide upon irradiation withactinic rays or radiation is described in JP-T-11-501909,JP-A-2002-268223 and JP-A-2003-246786. Furthermore, in JP-A-6-242606,JP-A-11-160861, U.S. Patent Application 2004/0087690A1, a specificorganic sulfonic acid is used.

In addition, as for the chemical amplification-type resist composition,a resist composition containing a specific amide compound is describedin JP-A-5-181263, WO01-004706, pamphlet and JP-A-11-327145.

However, many points still remain unsatisfied, and improvement isdemanded with respect to the pattern profile, line edge roughness anddefocus latitude depended on line pitch.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a photosensitivecomposition improved in the pattern profile, line edge roughness anddefocus latitude depended on line pitch and enhanced in the sensitivityand resolution at the exposure with EUV light, a compound for use in thephotosensitive composition, and a pattern forming method using thephotosensitive composition.

The present invention is as follows.

(1) A photosensitive composition comprising:

(A) a compound capable of generating a compound represented by formula(I) upon irradiation with actinic rays or radiation:

wherein R₁ and R₂ each independently represents a monovalent organicgroup, provided that at least either one of R₁ and R₂ has a protonacceptor functional group, R₁ and R₂ may combine to form a ring and thering formed may have a proton acceptor functional group; and

X₁ and X₂ each independently represents —CO— or —SO₂—.

(2) The photosensitive composition as described in (1) above,

wherein the compound represented by formula (I) is represented byformula (II):

wherein R₁ and R₃ each independently represents a monovalent organicgroup, provided that at least either one of R₁ and R₃ has a protonacceptor functional group, R₁ and R₃ may combine to form a ring and thering formed may have a proton acceptor functional group;

X₁, X₂ and X₃ each independently represents —CO— or —SO₂—;

A represents a divalent linking group;

B represents a single bond, an oxygen atom or —N(Rx)-;

Rx represents a hydrogen atom or a monovalent organic group;

when B is —N(Rx)-, R₃ and Rx may combine to form a ring; and

n represents 0 or 1.

(3) The photosensitive composition as described in (1) or (2) above,

wherein the compound capable of generating a compound represented byformula (I) or (II) upon irradiation with actinic rays or radiation is asulfonium salt compound of the compound represented by formula (I) or(II) or an iodonium salt compound of the compound represented by formula(I) or (II).

(4) A compound capable of generating a compound represented by formula(I) or (II) upon irradiation with actinic rays or radiation:

wherein R₁ and R₂ each independently represents a monovalent organicgroup, provided that at least either one of R₁ and R₂ has a protonacceptor functional group, R₁ and R₂ may combine to form a ring and thering formed may have a proton acceptor functional group; and

X₁ and X₂ each independently represents —CO— or —SO₂—;

wherein R₁ and R₃ each independently represents a monovalent organicgroup, provided that at least either one of R₁ and R₃ has a protonacceptor functional group, R₁ and R₃ may combine to form a ring and thering formed may have a proton acceptor functional group;

X₁, X₂ and X₃ each independently represents —CO— or —SO₂—;

A represents a divalent linking group;

B represents a single bond, an oxygen atom or —N(Rx)-;

Rx represents a hydrogen atom or a monovalent organic group;

when B is —N(Rx)-, R₃ and Rx may combine to form a ring; and

n represents 0 or 1.

(5) A pattern forming method comprising:

forming a photosensitive film from a photosensitive composition asdescribed in any of (1) to (3) above; and

exposing and developing the photosensitive film.

Furthermore, the preferred embodiment includes the followingconstitutions.

(6) The photosensitive composition as described in any of (1) to (3)above, which further comprises (B) a compound capable of generating anacid upon irradiation with actinic rays or radiation.

(7) The photosensitive composition as described in (6) above,

wherein the compound as the component (B) is a sulfonium salt offluoro-substituted alkanesulfonic acid, fluorine-substitutedbenzenesulfonic acid or fluorine-substituted imide acid.

(8) The photosensitive composition as described in any of (1) to (3),(6) and (7) above, which is a positive photosensitive composition andfurther comprises (C) a resin capable of decomposing under an action ofan acid to increase a solubility of the resin (C) in an alkalideveloper.

(9) The photosensitive composition as described in (8) above,

wherein the resin as the component (C) has a fluorine atom in a main orside chain.

(10) The photosensitive composition as described in (9) above,

wherein the resin as the component (C) has a hexafluoroisopropanolstructure.

(11) The photosensitive composition as described in (8) above,

wherein the resin as the component (C) has a hydroxystyrene structuralunit.

(12) The photosensitive composition as described in (8) above,

wherein the resin as the component (C) has at least one repeating unitselected from 2-alkyl-2-adamantyl (meth)acrylate anddialkyl(1-adamantyl)methyl (meth)acrylate.

(13) The photosensitive composition as described in (8) above,

wherein the resin as the component (C) has a monocyclic or polycyclicalicyclic hydrocarbon structure.

(14) The photosensitive composition as described in (13) above,

wherein the resin as the component (C) has at least one repeating unitselected from 2-alkyl-2-adamantyl (meth)acrylate anddialkyl(1-adamantyl)methyl (meth)acrylate, at least one repeating unithaving a lactone structure and at least one repeating unit having ahydroxyl group.

(15) The photosensitive composition as described in (14) above,

wherein the resin as the component (C) further has a repeating unithaving a carboxyl group.

(16) The photosensitive composition as described in (8) above,

wherein the resin as the component (C) has a silicon atom in a main orside chain.

(17) The photosensitive composition as described in (8) above,

wherein the resin as the component (C) has a repeating unit having alactone structure.

(18) The photosensitive composition as described in any of (8) to (17)above, which further comprises (D) a dissolution inhibiting compoundcapable of decomposing under an action of an acid to increase asolubility of the compound (D) in an alkali developer and having amolecular weight of 3,000 or less.

(19) The photosensitive composition as described in any of (1) to (3),(6) and (7) above, which is a positive photosensitive composition andfurther comprises:

(E) a resin soluble in an alkali developer; and

(D) a dissolution inhibiting compound capable of decomposing under anaction of an acid to increase a solubility of the compound (D) in analkali developer and having a molecular weight of 3,000 or less.

(20) The photosensitive composition as described in any of (1) to (3),(6) and (7) above, which is a negative photosensitive composition andfurther comprises:

(E) a resin soluble in an alkali developer; and

(F) an acid crosslinking agent capable of crosslinking with the resinsoluble in an alkali developer under an action of an acid.

(21) The photosensitive composition as described in any of (1) to (3)and (6) to (20) above, which further comprises at least one of (G) abasic compound and (H) at least one of a fluorine-containing surfactantand a silicon-containing surfactant.

(22) The photosensitive composition as described in (21) above,

wherein the basic compound (G) is a compound having a structure selectedfrom an imidazole structure, a diazabicyclo structure, an oniumhydroxide structure, an onium carboxylate structure, a trialkylaminestructure, an aniline structure and a pyridine structure, an alkylaminederivative having at least one of a hydroxyl group and an ether bond oran aniline derivative having at least one of a hydroxyl group and anether bond.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is a schematic view of the two-beam interference exposuretesting apparatus.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described in detail below.

In the present invention, when a group (atomic group) is denoted withoutspecifying whether substituted or unsubstituted, the group includes botha group having no substituent and a group having a substituent. Forexample, an “alkyl group” includes not only an alkyl group having nosubstituent (unsubstituted alkyl group) but also an alkyl group having asubstituent (substituted alkyl group).

The positive photosensitive composition, preferably positive resistcomposition, of the present invention comprises (A) a compound capableof generating a compound represented by formula (I) upon irradiationwith actinic rays or radiation, (B) a compound capable of generating anacid upon irradiation with actinic rays or radiation, (C) a compoundcapable of decomposing under the action of an acid to increase thesolubility in an alkali developer, and, if desired, (D) a dissolutioninhibiting compound capable of decomposing under the action of an acidto increase the solubility in an alkali developer and having a molecularweight of 3,000 or less, or comprises (A) a compound capable ofgenerating a compound represented by formula (I) upon irradiation withactinic rays or radiation, (B) a compound capable of generating an acidupon irradiation with actinic rays or radiation, (E) a resin soluble inan alkali developer, and (D) a dissolution inhibiting compound capableof decomposing under the action of an acid to increase the solubility inan alkali developer and having a molecular weight of 3,000 or less.

The negative photosensitive composition, preferably negative resistcomposition, of the present invention comprises (A) a compound capableof generating a compound represented by formula (I) upon irradiationwith actinic rays or radiation, (B) a compound capable of generating anacid upon irradiation with actinic rays or radiation, (E) a resinsoluble in an alkali developer, and (F) an acid crosslinking agentcapable of crosslinking with the alkali developer-soluble resin underthe action of an acid.

[1] (A) Compound Capable of Generating a Compound Represented by Formula(I) Upon Irradiation with Actinic Rays or Radiation

The photosensitive composition of the present invention comprises acompound (hereinafter referred to as a “compound (A)”) capable ofgenerating a compound represented by the following formula (I) uponirradiation with actinic rays or radiation.

In formula (I), R₁ and R₂ each independently represents a monovalentorganic group, provided that at least either one of R₁ and R₂ has aproton acceptor functional group. R₁ and R₂ may combine to form a ringand the ring formed may have a proton acceptor functional group.

X₁ and X₂ each independently represents —CO— or —SO₂—.

The monovalent organic group as R₁ and R₂ in formula (I) is preferably amonovalent organic group having a carbon number of 1 to 40, and examplesthereof include an alkyl group, a cycloalkyl group, an aryl group, anaralkyl group and an alkenyl group.

The alkyl group as R₁ and R₂, which may have a substituent, ispreferably a linear or branched alkyl group having a carbon number of 1to 30 and may contain an oxygen atom, a sulfur atom or a nitrogen atomin the alkyl chain. Specific examples thereof include a linear alkylgroup such as methyl group, ethyl group, n-propyl group, n-butyl group,n-pentyl group, n-hexyl group, n-octyl group, n-dodecyl group,n-tetradecyl group and n-octadecyl group; and a branched alkyl groupsuch as isopropyl group, isobutyl group, tert-butyl group, neopentylgroup and 2-ethylhexyl group.

The cycloalkyl group as R₁ and R₂, which may have a substituent, ispreferably a cycloalkyl group having a carbon number of 3 to 20 and maycontain an oxygen atom or a nitrogen atom in the ring. Specific examplesthereof include a cyclopropyl group, a cyclopentyl group, a cyclohexylgroup, a norbornyl group and an adamantyl group.

The aryl group as R₁ and R₂, which may have a substituent, is preferablyan aryl group having a carbon number of 6 to 14, and examples thereofinclude a phenyl group and a naphthyl group.

The aralkyl group as R₁ and R₂, which may have a substituent, ispreferably an aralkyl group having a carbon number of 7 to 20, andexamples thereof include a benzyl group, a phenethyl group, anaphthylmethyl group and a naphthylethyl group.

The alkenyl group as R₁ and R₂, which may have a substituent, includes agroup having a double bond at an arbitrary position of the alkyl groupdescribed above.

Examples of the substituent which the above-described groups each mayhave include a halogen atom, a hydroxyl group, a nitro group, a cyanogroup, a carboxy group, a carbonyl group, a cycloalkyl group (preferablyhaving a carbon number of 3 to 10), an aryl group (preferably having acarbon number of 6 to 14), an alkoxy group (preferably having a carbonnumber of 1 to 10), an acyl group (preferably having a carbon number of2 to 20), an acyloxy group (preferably having a carbon number of 2 to10), an alkoxycarbonyl group (preferably having a carbon number of 2 to20) and an aminoacyl group (preferably having a carbon number of 2 to10). As for the cyclic structure in the aryl group, cycloalkyl group andthe like, examples of the substituent further include an alkyl group(preferably having a carbon number of 1 to 10). As for the aminoacylgroup, examples of the substituent further include an alkyl group(preferably having a carbon number of 1 to 10). Examples of the alkylgroup having a substituent include a perfluoroalkyl group such asperfluoromethyl group, perfluoroethyl group, perfluoropropyl group andperfluorobutyl group.

Either one monovalent organic group of R₁ and R₂ has a proton acceptorfunctional group. The proton acceptor functional group is a groupcapable of electrostatically interacting with a proton or a functionalgroup having a lone pair of electrons, and examples thereof include afunctional group having a microcyclic structure such as cyclicpolyether, and a functional group containing a nitrogen atom having alone pair of electrons less contributing to π-conjugation. Examples ofthe nitrogen atom having a lone pair of electrons less contributing toπ-conjugation include a nitrogen atom having a partial structurerepresented by either one of the following formulae:

Preferred examples of the partial structure of the proton acceptorfunctional group include a crown ether structure, an aza-crown etherstructure, a tertiary amine structure, a secondary amine structure, aprimary amine structure, a pyridine structure, an imidazole structure, apyrazine structure and an aniline structure. The carbon number thereofis preferably from 4 to 30. Examples of the group containing such astructure include an alkyl group, a cycloalkyl group, an aryl group, anaralkyl group and an alkenyl group. The alkyl group, cycloalkyl group,aryl group, aralkyl group and alkenyl group are the same as thosedescribed above.

Examples of the substituent which the above-described groups each mayhave include a halogen atom, a hydroxyl group, a nitro group, a cyanogroup, a carboxy group, a carbonyl group, a cycloalkyl group (preferablyhaving a carbon number of 3 to 10), an aryl group (preferably having acarbon number of 6 to 14), an alkoxy group (preferably having a carbonnumber of 1 to 10), an acyl group (preferably having a carbon number of2 to 20), an acyloxy group (preferably having a carbon number of 2 to10), an alkoxycarbonyl group (preferably having a carbon number of 2 to20) and an aminoacyl group (preferably having a carbon number of 2 to20). As for the cyclic structure in the aryl group, cycloalkyl group andthe like, examples of the substituent further include an alkyl group(preferably having a carbon number of 1 to 20). As for the aminoacylgroup, examples of the substituent further include an alkyl group(preferably having a carbon number of 1 to 20).

The proton acceptor functional group may be substituted by an organicgroup having a bond which is breakable by an acid. Examples of theorganic group having a bond breakable by an acid include an amide group,an ester group (preferably tertiary alkyloxycarbonyl group), an acetalgroup (preferably 1-alkyloxy-alkyloxy group), a carbamoyl group and acarbonate group.

When R₁ and R₂ combine to form a ring and the ring formed has a protonacceptor functional group, examples of the structure therefor include astructure where the organic groups of R₁ and R₂ are further bondedthrough an alkylene group, an oxy group or an imino group.

In formula (I), at least either one of X₁ and X₂ is preferably —SO₂—.

The compound represented by formula (I) is preferably represented by thefollowing formula (II):

In formula (II), R₁ and R₃ each independently represents a monovalentorganic group, provided that at least either one of R₁ and R₃ has aproton acceptor functional group. R₁ and R₃ may combine to form a ringand the ring formed may have a proton acceptor functional group.

X₁, X₂ and X₃ each independently represents —CO— or —SO₂—.

A represents a divalent linking group.

B represents a single bond, an oxygen atom or —N(Rx)-.

Rx represents a hydrogen atom or a monovalent organic group.

when B is —N(Rx)-, R₃ and Rx may combine to form a ring.

n represents 0 or 1.

R₁ has the same meaning as R₁ in formula (I).

Examples of the organic group of R₃ are the same as those of the organicgroup of R₁ and R₂ in formula (I).

The divalent linking group as A is preferably a divalent organic grouphaving a carbon number of 1 to 8 and containing a fluorine atom, andexamples thereof include an alkylene group having a carbon number of 1to 8 and containing a fluorine atom, and a phenylene group having afluorine atom. The divalent linking group is more preferably an alkylenegroup having a fluorine atom, and the carbon number thereof ispreferably from 2 to 6, more preferably from 2 to 4. The alkylene groupmay contain a linking group such as oxygen atom and sulfur atom, in thealkylene chain. The alkylene group is preferably an alkylene group wherefrom 30 to 100% by number of the hydrogen atom is replaced by a fluorineatom, more preferably a perfluoroakylene group, still more preferably aperfluoroethylene group, a perfluoropropylene group or aperfluorobutylene group.

The monovalent organic group as Rx is preferably a monovalent organicgroup having a carbon number of 4 to 30, and examples thereof include analkyl group, a cycloalkyl group, an aryl group, an aralkyl group and analkenyl group. Examples of the alkyl group, cycloalkyl group, arylgroup, aralkyl group and alkenyl group are the same as those describedabove.

In formula (II), X₁, X₂ and X₃ each is preferably —SO₂—.

Specific examples of the compounds represented by formulae (I) and (II)are set forth below, but the present invention is not limited thereto.

The compound capable of generating a compound represented by formula (I)or (II) upon irradiation with actinic rays or radiation is preferably asulfonium salt compound of the compound represented by formula (I) or(II), or an iodonium salt compound of the compound represented byformula (I) or (II).

The compound capable of generating a compound represented by formula (I)or (II) upon irradiation with actinic rays or radiation is morepreferably a compound represented by the following formula (A1) or (A2):

In formula (A1), R₂₀₁, R₂₀₂ and R₂₀₃ each independently represents anorganic group.

X⁻ represents an anion of the compound represented by formula (I) or(II).

The carbon number of the organic group as R₂₀₁, R₂₀₂ and R₂₀₃ isgenerally from 1 to 30, preferably from 1 to 20.

Two members out of R₂₀₁ to R₂₀₃ may combine to form a ring structure,and the ring may contain an oxygen atom, a sulfur atom, an ester bond,an amide bond or a carbonyl group. Examples of the group formed bycombining two members out of R₂₀₁ to R₂₀₃ include an alkylene group(e.g., butylene, pentylene).

Specific examples of the organic group as R₂₀₁, R₂₀₂ and R₂₀₃ includethe corresponding groups in the compounds (A1a), (A1b) and (A1c)described later.

The compound may be a compound having a plurality of structuresrepresented by formula (A1). For example, the compound may be a compoundhaving a structure that at least one of R₂₀₁ to R₂₀₃ in the compoundrepresented by formula (A1) is bonded to at least one of R₂₀₁ to R₂₀₃ inanother compound represented by formula (A1).

The component (A1) is more preferably a compound (A1a), (A1b) or (A1c)described below.

The compound (A1a) is an arylsulfonium compound where at least one ofR₂₀₁ to R₂₀₃ in formula (A1) is an aryl group, that is, a compoundhaving arylsulfonium as the cation.

In the arylsulfonium compound, R₂₀₁ to R₂₀₃ all may be an aryl group ora part of R₂₀₁ to R₂₀₃ may be an aryl group with the remaining being analkyl group or a cycloalkyl group.

Examples of the arylsulfonium compound include a triarylsulfoniumcompound, a diarylalkylsulfonium compound, a diarylcycloalkylsulfoniumcompound, an aryldialkyl-sulfonium compound, anaryldicycloalkylsulfonium compound and an arylalkylcycloalkylsulfoniumcompound.

The aryl group in the arylsulfonium compound is preferably a phenylgroup or a naphthyl group, more preferably a phenyl group. The arylgroup may be an aryl group having a heterocyclic structure containing anoxygen atom, a nitrogen atom, a sulfur atom or the like. Examples of thearyl group having a heterocyclic structure include a pyrrole residue (agroup formed by removing one hydrogen atom from a pyrrole), a furanresidue (a group formed by removing one hydrogen atom from a furan), athiophene residue (a group formed by removing one hydrogen atom from athiophene), an indole residue (a group formed by removing one hydrogenatom from an indole), a benzofuran residue (a group formed by removingone hydrogen atom from a benzofuran) and a benzothiophene residue (agroup formed by removing one hydrogen atom from a benzothiophene). Inthe case where the arylsulfonium compound has two or more aryl groups,these two or more aryl groups may be the same of different.

The alkyl group which is present, if desired, in the arylsulfoniumcompound is preferably a linear or branched alkyl group having a carbonnumber of 1 to 15, and examples thereof include a methyl group, an ethylgroup, a propyl group, an n-butyl group, a sec-butyl group and atert-butyl group.

The cycloalkyl group which is present, if desired, in the arylsulfoniumcompound is preferably a cycloalkyl group having a carbon number of 3 to15, such as cyclopropyl group, cyclobutyl group and cyclohexyl group.

The aryl group, alkyl group and cycloalkyl group of R₂₀₁ to R₂₀₃ eachmay have, as the substituent, an alkyl group (for example, an alkylgroup having a carbon number of 1 to 15), a cycloalkyl group (forexample, a cycloalkyl group having a carbon number of 3 to 15), an arylgroup (for example, an aryl group having a carbon number of 6 to 14), analkoxy group (for example, an alkoxy group having a carbon number of 1to 15), a halogen atom, a hydroxyl group or a phenylthio group. Thesubstituent is preferably a linear or branched alkyl group having acarbon number of 1 to 12, a cycloalkyl group having a carbon number of 3to 12, or a linear, branched or cyclic alkoxy group having a carbonnumber of 1 to 12, and most preferably an alkyl group having a carbonnumber of 1 to 4, or an alkoxy group having a carbon number of 1 to 4.The substituent may be substituted to any one of three members R₂₀₁ toR₂₀₃ or may be substituted to all of these three members. In the casewhere R₂₀₁ to R₂₀₃ are an aryl group, the substituent is preferablysubstituted at the p-position of the aryl group.

The compound (A1b) is described below.

The compound (A1b) is a compound when R₂₀₁ to R₂₀₃ in formula (A1) eachindependently represents an organic group having no aromatic ring. Thearomatic ring as used herein includes an aromatic ring having aheteroatom.

The organic group as R₂₀₁ to R₂₀₃ having no aromatic ring has a carbonnumber of generally from 1 to 30, preferably from 1 to 20.

R₂₀₁ to R₂₀₃ each independently represents preferably an alkyl group, acycloalkyl group, an allyl group or a vinyl group, more preferably alinear or branched 2-oxoalkyl group, a 2-oxocycloalkyl group or analkoxycarbonylmethyl group, still more preferably a linear or branched2-oxoalkyl group.

The alkyl group as R₂₀₁ to R₂₀₃ may be either linear or branched and ispreferably a linear or branched alkyl group having a carbon number of 1to 20 (e.g., methyl, ethyl, propyl, butyl, pentyl), more preferably alinear or branched 2-oxoalkyl group or an alkoxycarbonylmethyl group.

The cycloalkyl group as R₂₀₁ to R₂₀₃ is preferably a cycloalkyl grouphaving a carbon number of 3 to 10 (e.g., cyclopentyl, cyclohexyl,norbornyl), more preferably a 2-oxocycloalkyl group.

The linear or branched 2-oxoalkyl group as R₂₀₁ to R₂₀₃ may have adouble bond in the chain, and preferred examples thereof include a grouphaving >C═O at the 2-position of the above-described alkyl group.

The 2-oxocycloalkyl group as R₂₀₁ to R₂₀₃ may have a double bond in thechain, and preferred examples thereof include a group having >C═O at the2-position of the above-described cycloalkyl group.

The alkoxy group in the alkoxycarbonylmethyl group as R₂₀₁ to R₂₀₃ ispreferably an alkoxy group having a carbon number of 1 to 5 (e.g.,methoxy, ethoxy, propoxy, butoxy, pentoxy).

R₂₀₁ to R₂₀₃ each may be further substituted by a halogen atom, analkoxy group (for example, an alkoxy group having a carbon number of 1to 5), an alkoxycarbonyl group (for example, an alkoxycarbonyl grouphaving a carbon number of 1 to 5), a hydroxyl group, a cyano group or anitro group.

The compound (A1c) is a compound represented by the following formula(A1c), and this is a compound having an arylacylsulfonium saltstructure.

In formula (A1c), R₂₁₃ represents an aryl group which may have asubstituent, and is preferably a phenyl group or a naphthyl group.

Preferred examples of the substituent on R₂₁₃ include an alkyl group, analkoxy group, an acyl group, a nitro group, a hydroxyl group, analkoxycarbonyl group and a carboxy group.

R₂₁₄ and R₂₁₅ each independently represents a hydrogen atom, an alkylgroup or a cycloalkyl group.

Y₂₀₁ and Y₂₀₂ each independently represents an alkyl group, a cycloalkylgroup, an aryl group or a vinyl group.

X⁻ represents an anion of the compound represented by formula (I) or(II).

R₂₁₃ and R₂₁₄ may combine with each other to form a ring structure, R₂₁₄and R₂₁₅ may combine with each other to form a ring structure, and Y₂₀₁and Y₂₀₂ may combine with each other to form a ring structure. The ringstructure formed may contain an oxygen atom, a sulfur atom, an esterbond or an amide bond. Examples of the group formed by combining eachpair of R₂₁₃ and R₂₁₄, R₂₁₄ and R₂₁₅, or Y₂₀₁ and Y₂₀₂ include abutylene group and a pentylene group.

The alkyl group as R₂₁₄, R₂₁₅, Y₂₀₁ and Y₂₀₂ is preferably a linear orbranched alkyl group having a carbon number of 1 to 20. The alkyl groupas Y₂₀₁ and Y₂₀₂ is more preferably a 2-oxoalkyl group having >C═O atthe 2-position of the alkyl group, an alkoxycarbonylalkyl group(preferably with the alkoxy group having a carbon number of 2 to 20), ora carboxyalkyl group.

The cycloalkyl group as R₂₁₄, R₂₁₅, Y₂₀₁ and Y₂₀₂ is preferably acycloalkyl group having a carbon number of 3 to 20.

The aryl group as Y₂₀₁ and Y₂₀₂ is preferably a phenyl group or anaphthyl group.

Y₂₀₁ and Y₂₀₂ each is preferably an alkyl group having a carbon numberof 4 or more, more preferably from 4 to 6, still more preferably from 4to 12.

At least either one of R₂₁₄ and R₂₁₅ is preferably an alkyl group, andmore preferably, R₂₁₄ and R₂₁₅ both are an alkyl group.

In formula (A2), R₂₀₄ and R₂₀₅ each independently represents an arylgroup, an alkyl group or a cycloalkyl group.

X⁻ represents an anion of the compound represented by formula (I) or(II).

The aryl group of R₂₀₄ and R₂₀₅ is preferably a phenyl group or anaphthyl group, more preferably a phenyl group. The aryl group of R₂₀₄and R₂₀₅ may be an aryl group having a heterocyclic structure containingan oxygen atom, a nitrogen atom, a sulfur atom or the like. Examples ofthe aryl group having a heterocyclic structure include a pyrrole residue(a group formed by removing one hydrogen atom from a pyrrole), a furanresidue (a group formed by removing one hydrogen atom from a furan), athiophene residue (a group formed by removing one hydrogen atom from athiophene), an indole residue (a group formed by removing one hydrogenatom from an indole), a benzofuran residue (a group formed by removingone hydrogen atom from a benzofuran) and a benzothiophene residue (agroup formed by removing one hydrogen atom from a benzothiophene).

The alkyl group as R₂₀₄ and R₂₀₅ may be either linear or branched and ispreferably a linear or branched alkyl group having a carbon number of 1to 10 (e.g., methyl, ethyl, propyl, butyl, pentyl).

The cycloalkyl group as R₂₀₄ and R₂₀₅ is preferably a cycloalkyl grouphaving a carbon number of 3 to 10 (e.g., cyclopentyl, cyclohexyl,norbornyl).

R₂₀₄ and R₂₀₅ each may have a substituent, and examples of thesubstituent which R₂₀₄ and R₂₀₅ each may have include an alkyl group(for example, an alkyl group having a carbon number of 1 to 15), acycloalkyl group (for example, a cycloalkyl group having a carbon numberof 3 to 15), an aryl group (for example, an aryl group having a carbonnumber of 6 to 15), an alkoxy group (for example, an alkoxy group havinga carbon number of 1 to 15), a halogen atom, a hydroxyl group and aphenylthio group.

The compound (A) is preferably a compound represented by formula (A1),more preferably a compound represented by any one of formulae (A1a) to(A1e).

Specific examples of the compound (A) are set forth below, but thepresent invention is not limited thereto.

The content of the compound (A) in the photosensitive composition of thepresent invention is preferably from 0.1 to 20 mass %, more preferablyfrom 0.1 to 10 mass %, based on the solid content of the composition.(In this specification, mass ratio is equal to weight ratio.)

The compound (A) is a novel compound.

The compound (A) can be easily synthesized by using a general sulfonicacid esterification reaction or sulfonamidation reaction. For example,this compound may be obtained by a method of selectively reacting onesulfonyl halide moiety of a bis-sulfonyl halide compound with an amine,alcohol or the like containing a partial structure represented byformula (I) to form a sulfonamide bond or a sulfonic acid ester bond,and then hydrolyzing the other sulfonyl halide moiety, or a method ofring-opening a cyclic sulfonic anhydride with an amine or alcoholcontaining a partial structure represented by formula (I). The amine oralcohol containing a partial structure represented by formula (I) can besynthesized by reacting an amine or alcohol with an anhydride (e.g.,(R′O₂C)₂O, R′O₂CCl) or an acid chloride compound under basic condition.

[2] (B) Compound Capable of Generating an Acid Upon Irradiation withActinic Rays or Radiation

The photosensitive composition of the present invention preferablycomprises a compound capable of generating an acid upon irradiation withactinic rays or radiation (hereinafter sometimes referred to as an “acidgenerator”).

The acid generator which can be used may be appropriately selected froma photoinitiator for photocationic polymerization, a photoinitiator forphotoradical polymerization, a photo-decoloring agent for coloringmatters, a photo-discoloring agent, a known compound capable ofgenerating an acid upon irradiation with actinic rays or radiation,which is used for microresist and the like, and a mixture thereof.

Examples thereof include diazonium salt, phosphonium salt, sulfoniumsalt, iodonium salt, imidosulfonate, oxime sulfonate, diazodisulfone,disulfone and o-nitrobenzyl sulfonate.

Also, a compound where the above-described group or compound capable ofgenerating an acid upon irradiation with actinic rays or radiation isintroduced into the polymer main or side chain, such as compoundsdescribed in U.S. Pat. No. 3,849,137, German Patent 3,914,407,JP-A-63-26653, JP-A-55-164824, JP-A-62-69263, JP-A-63-146038,JP-A-63-163452, JP-A-62-153853 and JP-A-63-146029, may be used.

Furthermore, a compound capable of generating an acid by the effect oflight described, for example, in U.S. Pat. No. 3,779,778 and EuropeanPatent 126,712 may also be used.

Among the compounds capable of generating an acid upon irradiation withactinic rays or radiation, preferred are the compounds represented bythe following formulae (ZI), (ZII) and (ZIII):

In formula (ZI), R₂₀₁, R₂₀₂ and R₂₀₃ each independently represents anorganic group.

The number of carbons in the organic group as R₂₀₁, R₂₀₂ and R₂₀₃ isgenerally from 1 to 30, preferably from 1 to 20.

Two members out of R₂₀₁ to R₂₀₃ may combine to form a ring structure,and the ring may contain an oxygen atom, a sulfur atom, an ester bond,an amide bond or a carbonyl group. Examples of the group formed bycombining two members out of R₂₀₁ to R₂₀₃ include an alkylene group(e.g., butylene, pentylene).

Z⁻ represents a non-nucleophilic anion.

Examples of the non-nucleophilic anion as Z⁻ include sulfonate anion,carboxylate anion, sulfonylimide anion, bis(alkylsulfonyl)imide anionand tris(alkylsulfonyl)methyl anion.

The non-nucleophilic anion is an anion having an extremely low abilityof causing a nucleophilic reaction and this anion can suppress thedecomposition in aging due to intramolecular nucleophilic reaction. Bythis anion, the aging stability of the resist is enhanced.

Examples of the sulfonate anion include aliphatic sulfonate anion,aromatic sulfonate anion and camphorsulfonate anion.

Examples of the carboxylate anion include aliphatic carboxylate anion,aromatic carboxylate anion and aralkylcarboxylate anion.

The aliphatic moiety in the aliphatic sulfonate anion may be an alkylgroup or a cycloalkyl group but is preferably an alkyl group having acarbon number of 1 to 30 or a cycloalkyl group having a carbon number of3 to 30, and examples thereof include a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, asec-butyl group, a pentyl group, a neopentyl group, a hexyl group, aheptyl group, an octyl group, a nonyl group, a decyl group, an undecylgroup, a dodecyl group, a tridecyl group, a tetradecyl group, apentadecyl group, a hexadecyl group, a heptadecyl group, an octadecylgroup, a nonadecyl group, an eicosyl group, a cyclopropyl group, acyclopentyl group, a cyclohexyl group, an adamantyl group, a norbornylgroup and a boronyl group.

The aromatic group in the aromatic sulfonate anion is preferably an arylgroup having a carbon number of 6 to 14, and examples thereof include aphenyl group, a tolyl group and a naphthyl group.

The alkyl group, cycloalkyl group and aryl group in the aliphaticsulfonate anion and aromatic sulfonate anion each may have asubstituent. Examples of the substituent for the alkyl group, cycloalkylgroup and aryl group in the aliphatic sulfonate anion and aromaticsulfonate anion include a nitro group, a halogen atom (e.g., fluorine,chlorine, bromine, iodine), a carboxyl group, a hydroxyl group, an aminogroup, a cyano group, an alkoxy group (preferably having a carbon numberof 1 to 5), a cycloalkyl group (preferably having a carbon number of 3to 15), an aryl group (preferably having a carbon number of 6 to 14), analkoxycarbonyl group (preferably having a carbon number of 2 to 7), anacyl group (preferably having a carbon number of 2 to 12) and analkoxycarbonyloxy group (preferably having a carbon number of 2 to 7).As for the aryl group or ring structure in each group, examples of thesubstituent further include an alkyl group (preferably having a carbonnumber of 1 to 15).

Examples of the aliphatic moiety in the aliphatic carboxylate anioninclude the same alkyl group and cycloalkyl group as in the aliphaticsulfonate anion.

Examples of the aromatic group in the aromatic carboxylate anion includethe same aryl group as in the aromatic sulfonate anion.

The aralkyl group in the aralkylcarboxylate anion is preferably anaralkyl group having a carbon number of 6 to 12, and examples thereofinclude a benzyl group, a phenethyl group, a naphthylmethyl group, anaphthylethyl group and a naphthylmethyl group.

The alkyl group, cycloalkyl group, aryl group and aralkyl group in thealiphatic carboxylate anion, aromatic carboxylate anion andaralkylcarboxylate anion each may have a substituent. Examples of thesubstituent for the alkyl group, cycloalkyl group, aryl group andaralkyl group in the aliphatic carboxylate anion, aromatic carboxylateanion and aralkylcarboxylate anion include the same halogen atom, alkylgroup, cycloalkyl group, alkoxy group and alkylthio group as in thearomatic sulfonate anion.

Examples of the sulfonylimide anion include saccharin anion.

The alkyl group in the bis(alkylsulfonyl)imide anion andtris(alkylsulfonyl)methyl anion is preferably an alkyl group having acarbon number of 1 to 5, and examples thereof include a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a sec-butyl group, a pentyl group and a neopentyl group.Examples of the substituent for such an alkyl group include a halogenatom, a halogen atom-substituted alkyl group, an alkoxy group and analkylthio group. Among these, an alkyl group substituted by a fluorineatom is preferred.

Other examples of the non-nucleophilic anion include fluorinatedphosphorus, fluorinated boron and fluorinated antimony.

The non-nucleophilic anion of Z⁻ is preferably an aliphatic sulfonateanion with the α-position of sulfonic acid being substituted by afluorine atom, an aromatic sulfonate anion substituted by a fluorineatom or a group having a fluorine atom, a bis(alkylsulfonyl)imide anionwith the alkyl group being substituted by a fluorine atom, or atris(alkylsulfonyl)methide anion with the alkyl group being substitutedby a fluorine atom, more preferably a perfluoroaliphatic sulfonate anionhaving a carbon number of 4 to 8 or a benzenesulfonate anion having afluorine atom, still more preferably nonafluorobutanesulfonate anion,perfluorooctanesulfonate anion, pentafluorobenzene-sulfonate anion or3,5-bis(trifluoromethyl)benzenesulfonate anion.

Examples of the organic group as R₂₀₁, R₂₀₂ and R₂₀₃ includecorresponding groups in the compounds (ZI-1), (ZI-2) and (ZI-3) whichare described later.

The compound may be a compound having a plurality of structuresrepresented by formula (Z1), for example, may be a compound having astructure that at least one of R₂₀₁ to R₂₀₃ in the compound representedby formula (Z1) is bonded to at least one of R₂₀₁ to R₂₀₃ in anothercompound represented by formula (Z1).

The component (Z1) is more preferably a compound (ZI-1), (ZI-2) or(ZI-3) described below.

The compound (ZI-1) is an arylsulfonium compound where at least one ofR₂₀₁ to R₂₀₃ in formula (Z1) is an aryl group, that is, a compoundhaving an arylsulfonium as the cation.

In the arylsulfonium compound, R₂₀₁ to R₂₀₃ all may be an aryl group ora part of R₂₀₁ to R₂₀₃ may be an aryl group with the remaining being analkyl group or a cycloalkyl group.

Examples of the arylsulfonium compound include a triarylsulfoniumcompound, a diarylalkylsulfonium compound, an aryldialkylsulfoniumcompound, a diarylcycloalkyl-sulfonium compound and anaryldicycloalkylsulfonium compound.

The aryl group in the arylsulfonium compound is preferably a phenylgroup or a naphthyl group, more preferably a phenyl group. The arylgroup may be an aryl group having a heterocyclic structure containing anoxygen atom, a nitrogen atom, a sulfur atom or the like. Examples of thearyl group having a heterocyclic structure include a pyrrole residue (agroup formed by removing one hydrogen atom from a pyrrole), a furanresidue (a group formed by removing one hydrogen atom from a furan), athiophene residue (a group formed by removing one hydrogen atom from athiophene), an indole residue (a group formed by removing one hydrogenatom from an indole), a benzofuran residue (a group formed by removingone hydrogen atom from a benzofuran) and a benzothiophene residue (agroup formed by removing one hydrogen atom from a benzothiophene). Inthe case where the arylsulfonium compound has two or more aryl groups,these two or more aryl groups may be the same of different.

The alkyl group or cycloalkyl group which is present, if desired, in thearylsulfonium compound is preferably a linear or branched alkyl grouphaving a carbon number of 1 to 15 or a cycloalkyl group having a carbonnumber of 3 to 15, and examples thereof include a methyl group, an ethylgroup, a propyl group, an n-butyl group, a sec-butyl group, a tert-butylgroup, a cyclopropyl group, a cyclobutyl group and a cyclohexyl group.

The aryl group, alkyl group and cycloalkyl group of R₂₀₁ to R₂₀₃ eachmay have, as the substituent, an alkyl group (for example, an alkylgroup having a carbon number of 1 to 15), a cycloalkyl group (forexample, a cycloalkyl group having a carbon number of 3 to 15), an arylgroup (for example, an aryl group having a carbon number of 6 to 14), analkoxy group (for example, an alkoxy group having a carbon number of 1to 15), a halogen atom, a hydroxyl group or a phenylthio group. Thesubstituent is preferably a linear or branched alkyl group having acarbon number of 1 to 12, a cycloalkyl group having a carbon number of 3to 12, or a linear, branched or cyclic alkoxy group having a carbonnumber of 1 to 12, more preferably an alkyl group having a carbon numberof 1 to 4, or an alkoxy group having a carbon number of 1 to 4. Thesubstituent may be substituted to any one of three members R₂₀₁ to R₂₀₃or may be substituted to all of these three members. In the case whereR₂₀₁ to R₂₀₃ are an aryl group, the substituent is preferablysubstituted at the p-position of the aryl group.

The compound (ZI-2) is described below.

The compound (ZI-2) is a compound where R₂₀₁ to R₂₀₃ in formula (ZI)each independently represents an organic group having no aromatic ring.The aromatic ring as used herein includes an aromatic ring containing aheteroatom.

The organic group as R₂₀₁ to R₂₀₃ having no aromatic ring has a carbonnumber of generally 1 to 30, preferably from 1 to 20.

R₂₀₁ to R₂₀₃ each independently represents preferably an alkyl group, acycloalkyl group, an allyl group or a vinyl group, more preferably alinear or branched 2-oxoalkyl group, a 2-oxocycloalkyl group or analkoxycarbonylmethyl group, still preferably a linear or branched2-oxoalkyl group.

The alkyl group and cycloalkyl group of R₂₀₁ to R₂₀₃ are preferably alinear or branched alkyl group having a carbon number of 1 to 10 (e.g.,methyl, ethyl, propyl, butyl, pentyl) and a cycloalkyl group having acarbon number of 3 to 10 (e.g., cyclopentyl, cyclohexyl, norbornyl). Thealkyl group is more preferably a 2-oxoalkyl group or analkoxycarbonylmethyl group. The cycloalkyl group is more preferably a2-oxocycloalkyl group.

The 2-oxoalkyl group may be either linear or branched and is preferablya group having >C═O at the 2-position of the above-described alkylgroup.

The 2-oxocycloalkyl group is preferably a group having >C═O at the2-position of the above-described cycloalkyl group.

The alkoxy group in the alkoxycarbonylmethyl group is preferably analkyl group having a carbon number of 1 to 5 (e.g., methoxy, ethoxy,propoxy, butoxy, pentoxy).

R₂₀₁ to R₂₀₃ each may be further substituted by a halogen atom, analkoxy group (for example, an alkoxy group having a carbon number of 1to 5), a hydroxyl group, a cyano group or a nitro group.

The compound (ZI-3) is a compound represented by the following formula(ZI-3), and this is a compound having a phenacylsulfonium saltstructure.

In formula (ZI-3), R_(1c) to R_(5c) each independently represents ahydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group or ahalogen atom.

R_(6c) and R_(7c) each independently represents a hydrogen atom, analkyl group or a cycloalkyl group.

R_(x) and R_(y) each independently represents an alkyl group, acycloalkyl group, an allyl group or a vinyl group.

Any two or more members out of R_(1c) to R_(5c) or each pair of R_(6c)and R_(7c), or R_(x) and R_(y) may combine with each other to form aring structure, and the ring structure may contain an oxygen atom, asulfur atom, an ester bond or an amide bond. Examples of the groupformed by combining any two or more members out of R_(1c) to R_(5c) orcombining each pair of R_(6c) and R_(7c), or R_(x) and R_(y) include abutylene group and a pentylene group.

Zc⁻ represents a non-nucleophilic anion, and examples thereof are thesame as those of the non-nucleophilic anion of Z⁻ in formula (ZI).

The alkyl group as R_(1c) to R_(7c) may be either linear or branched andthis is, for example, an alkyl group having a carbon number of 1 to 20,preferably a linear or branched alkyl group having a carbon number of 1to 12 (e.g., methyl, ethyl, linear or branched propyl, linear orbranched butyl, linear or branched pentyl). The cycloalkyl group is, forexample, a cycloalkyl group having a carbon number of 3 to 8 (e.g.,cyclopentyl, cyclohexyl).

The alkoxy group as R_(1c) to R_(5c) may be linear, branched or cyclicand this is, for example, an alkoxy group having a carbon number of 1 to10, preferably a linear or branched alkoxy group having a carbon numberof 1 to 5 (e.g., methoxy, ethoxy, linear or branched propoxy, linear orbranched butoxy, linear or branched pentoxy) or a cyclic alkoxy grouphaving a carbon number of 3 to 8 (e.g., cyclopentyloxy, cyclohexyloxy).

A compound where any one of R_(1c) to R_(5c) is a linear or branchedalkyl group, a cycloalkyl group or a linear, branched or cyclic alkoxygroup is preferred, and a compound where the sum of carbon numbers ofR_(1c) to R_(5c) is from 2 to 15 is more preferred. In this case, thesolubility in a solvent is more enhanced and the generation of particlesduring storage can be suppressed.

Examples of the alkyl group and cycloalkyl group as R_(x) and R_(y)include the same alkyl group and cycloalkyl group as in R_(1c) toR_(7c). Among these, a 2-oxoalkyl group, a 2-oxocycloalkyl group and analkoxycarbonylmethyl group are preferred.

Examples of the 2-oxoalkyl group and 2-oxocycloalkyl group include agroup having >C═O at the 2-position of the alkyl group or cycloalkylgroup as R_(1c) to R_(7c).

Examples of the alkoxy group in the alkoxycarbonylmethyl group includethe same alkoxy group as in R_(1c) to R_(5c).

R_(x) and R_(y) each is preferably an alkyl or cycloalkyl group having acarbon number of 4 or more, more preferably 6 or more, still morepreferably 8 or more.

In formulae (ZII) and (ZIII), R₂₀₄ to R₂₀₇ each independently representsan aryl group, an alkyl group or a cycloalkyl group.

The aryl group of R₂₀₄ to R₂₀₇ is preferably a phenyl group or anaphthyl group, more preferably a phenyl group. The aryl group of R₂₀₄and R₂₀₇ may be an aryl group having a heterocyclic structure containingan oxygen atom, a nitrogen atom, a sulfur atom or the like. Examples ofthe aryl group having a heterocyclic structure include a pyrrole residue(a group formed by removing one hydrogen atom from a pyrrole), a furanresidue (a group formed by removing one hydrogen atom from a furan), athiophene residue (a group formed by removing one hydrogen atom from athiophene), an indole residue (a group formed by removing one hydrogenatom from an indole), a benzofuran residue (a group formed by removingone hydrogen atom from a benzofuran) and a benzothiophene residue (agroup formed by removing one hydrogen atom from a benzothiophene).

The alkyl group and cycloalkyl group in R₂₀₄ to R₂₀₇ are preferably alinear or branched alkyl group having a carbon number of 1 to 10 (e.g.,methyl, ethyl, propyl, butyl, pentyl) and a cycloalkyl group having acarbon number of 3 to 10 (e.g., cyclopentyl, cyclohexyl, norbornyl).

The aryl group, alkyl group and cycloalkyl group of R₂₀₄ to R₂₀₇ eachmay have a substituent. Examples of the substituent which the arylgroup, alkyl group and cycloalkyl group of R₂₀₄ to R₂₀₇ each may haveinclude an alkyl group (for example, an alkyl group having a carbonnumber of 1 to 15), a cycloalkyl group (for example, a cycloalkyl grouphaving a carbon number of 3 to 15), an aryl group (for example, an arylgroup having a carbon number of 6 to 15), an alkoxy group (for example,an alkoxy group having a carbon number of 1 to 15), a halogen atom, ahydroxyl group and a phenylthio group.

Z⁻ represents a non-nucleophilic anion, and examples thereof are thesame as those of the non-nucleophilic anion of Z⁻ in formula (ZI).

Other examples of the compound capable of generating an acid uponirradiation with actinic rays or radiation, which can be used, includethe compounds represented by the following formulae (ZIV), (ZV) and(ZVI):

In formulae (ZIV) to (ZVI), Ar₃ and Ar₄ each independently represents anaryl group.

R₂₀₆, R₂₀₇ and R₂₀₈ each independently represents an alkyl group, acycloalkyl group or an aryl group.

A represents an alkylene group, an alkenylene group or an arylene group.

Among the compounds capable of generating an acid upon irradiation withactinic rays or radiation, more preferred are the compounds representedby formulae (ZI) to (ZIII).

The compound capable of generating an acid upon irradiation with actinicrays or radiation is preferably a compound capable of generating an acidhaving one sulfonic acid group or imide group, more preferably acompound capable of generating a monovalent perfluoroalkanesulfonicacid, a compound capable of generating a monovalent aromatic sulfonicacid substituted by a fluorine atom or a fluorine atom-containing group,or a compound capable of generating a monovalent imide acid substitutedby a fluorine atom or a fluorine atom-containing group. In particular,the usable acid generator preferably generates a fluoro-substitutedalkanesulfonic acid, a fluoro-substituted benzenesulfonic acid or afluoro-substituted imide acid, each having a pKa of −1 or less, and inthis case, the sensitivity can be enhanced.

Among the compounds capable of generating an acid upon irradiation withactinic rays or radiation, particularly preferred compounds are setforth below.

One acid generator may be used alone or two or more kinds of acidgenerators may be used in combination.

The content of the acid generator in the photosensitive composition ispreferably from 0.1 to 20 mass %, more preferably from 0.5 to 10 mass %,still more preferably from 1 to 7 mass %, based on the entire solidcontent of the photosensitive composition.

[3] (C) Resin Capable of Decomposing Under the Action of an Acid toIncrease the Solubility in an Alkali Developer (Hereinafter SometimesReferred to as a “Component (C)”)

The resin capable of decomposing under the action of an acid to increasethe solubility in an alkali developer, which is used in the positivephotosensitive composition of the present invention, is a resin having agroup capable of decomposing under the action of an acid (hereinaftersometimes referred to as an “acid-decomposable group”), in ether one orboth of the main chain and the side chain thereof. Of these, a resinhaving an acid-decomposable group in the side chain is preferred.

The group capable of decomposing under the action of an acid ispreferably a group resulting from replacement of the hydrogen atom of a—COOH or —OH group by a group which splits off by the effect of an acid.

In the present invention, the acid-decomposable group is preferably anacetal group or a tertiary ester group.

In the case where the group capable of decomposing under the action ofan acid is bonded as a side chain, the mother resin is an alkali-solubleresin having an —OH or —COOH group in the side chain. Examples thereofinclude an alkali-soluble resin described later.

The alkali dissolution rate of such an alkali-soluble resin ispreferably 170 A/sec or more, more preferably 330 A/sec or more (A isangstrom), as measured (at 23° C.) in 0.261N tetramethylammoniumhydroxide (TMAH).

From this standpoint, the alkali-soluble resin is preferably analkali-soluble resin having a hydroxystyrene structural unit, such aso-, m- or p-poly(hydroxystyrene) or a copolymer thereof, hydrogenatedpoly(hydroxystyrene), halogen- or alkyl-substitutedpoly(hydroxystyrene), partially O-alkylated or O-acylatedpoly(hydroxystyrene), styrene-hydroxystyrene copolymer,α-methylstyrene-hydroxystyrene copolymer and hydrogenated novolak resin;or an alkali-soluble resin containing a repeating unit having a carboxylgroup, such as (meth)acrylic acid and norbornene carboxylic acid.

Preferred examples of the repeating unit having an acid-decomposablegroup for use in the present invention includetert-butoxycarbonyloxystyrene, 1-alkoxyethoxystyrene and tertiary alkyl(meth)acrylate. Among these, 2-alkyl-2-adamantyl (meth)acrylate anddialkyl(1-adamantyl)methyl (meth)acrylate are more preferred.

The component (C) for use in the present invention can be obtained byreacting an acid-decomposable group precursor with an alkali-solubleresin or copolymerizing an acid-decomposable group-bonded alkali-solubleresin monomer with various monomers, and this is disclosed in EuropeanPatent 254853, JP-A-2-25850, JP-A-3-223860 and JP-A-4-251259.

In the case of irradiating the positive photosensitive composition ofthe present invention with KrF excimer laser light, electron beam, X-rayor high-energy light at a wavelength of 50 nm or less (e.g., EUV), theresin as the component (C) preferably has a hydroxystyrene repeatingunit, and the resin is more preferably a copolymer ofhydroxystyrene/hydroxystyrene protected by an acid-decomposable group,or hydroxystyrene/tertiary alkyl methacrylate.

Specific examples of the component (C) for use in the present inventionare set forth below, but the present invention is not limited thereto.

In these specific examples, “tBu” indicates a tert-butyl group.

The content of the group capable of decomposing under the action of anacid is expressed by B/(B+S) using the number (B) of acid-decomposablegroups in the resin and the number (S) of alkali-soluble groups notprotected by a group which splits off by the effect of an acid. Thecontent is preferably from 0.01 to 0.7, more preferably from 0.05 to0.50, still more preferably from 0.05 to 0.40.

In the case of irradiating the positive photosensitive composition ofthe present invention with ArF excimer laser light, the resin as thecomponent (C) is preferably a resin having a monocyclic or polycyclicalicyclic hydrocarbon structure and undergoing decomposition by theeffect of an acid to increase the solubility in an alkali developer.

The resin having a monocyclic or polycyclic alicyclic hydrocarbonstructure and undergoing decomposition by the effect of an acid toincrease the solubility in an alkali developer (hereinafter sometimesreferred to as an “alicyclic hydrocarbon-based acid-decomposable resin”)is preferably a resin containing at least one repeating unit selectedfrom the group consisting of a repeating unit having an alicyclichydrocarbon-containing partial structure represented by any one of thefollowing formulae (pI) to (pV), and a repeating unit represented by thefollowing formula (II-AB):

In formulae (pI) to (pV), R₁₁ represents a methyl group, an ethyl group,an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup or a sec-butyl group. Z represents an atomic group necessary forforming a cycloalkyl group together with the carbon atom.

R₁₂ to R₁₆ each independently represents a linear or branched alkylgroup having a carbon number of 1 to 4 or a cycloalkyl group, providedthat at least one of R₁₂ to R₁₄ or either one of R₁₅ and R₁₆ representsa cycloalkyl group.

R₁₇ to R₂₁ each independently represents a hydrogen atom, a linear orbranched alkyl group having a carbon number of 1 to 4 or a cycloalkylgroup, provided that at least one of R₁₇ to R₂₁ represents a cycloalkylgroup and that either one of R₁₉ and R₂₁ represents a linear or branchedalkyl group having a carbon number of 1 to 4 or a cycloalkyl group.

R₂₂ to R₂₅ each independently represents a hydrogen atom, a linear orbranched alkyl group having a carbon number of 1 to 4 or a cycloalkylgroup, provided that at least one of R₂₂ to R₂₅ represents a cycloalkylgroup. R₂₃ and R₂₄ may combine with each other to form a ring.

In formula (II-AB), R₁₁′ and R₁₂′ each independently represents ahydrogen atom, a cyano group, a halogen atom or an alkyl group.

Z′ represents an atomic group for forming an alicyclic structure,containing two bonded carbon atoms (C—C).

Formula (II-AB) is preferably the following formula (II-AB1) or(II-AB2).

In formulae (II-AB1) and (II-AB2), R₁₃′ to R₁₆′ each independentlyrepresents a hydrogen atom, a halogen atom, a cyano group, a hydroxylgroup, —COOH, —COOR₅, a group capable of decomposing under the action ofan acid, —C(═O)—X-A′—R₁₇′, an alkyl group or a cycloalkyl group, and atleast two members out of R₁₃′ to R₁₆′ may combine to form a ring.

R₅ represents an alkyl group, a cycloalkyl group or a group having alactone structure.

X represents an oxygen atom, a sulfur atom, —NH—, —NHSO₂— or —NHSO₂NH—.

A′ represents a single bond or a divalent linking group.

R₁₇′ represents —COOH, —COOR₅, —CN, a hydroxyl group, an alkoxy group,—CO—NH—R₆, —CO—NH—SO₂—R₆ or a group having a lactone structure.

R₆ represents an alkyl group or a cycloalkyl group.

n represents 0 or 1.

In formulae (pI) to (pV), the alkyl group of R₁₂ to R₂₅ is a linear orbranched alkyl group having from 1 to 4 carbon atoms, and examplesthereof include a methyl group, an ethyl group, a propyl group, ann-butyl group, a sec-butyl group and a tert-butyl group.

The cycloalkyl group of R₁₁ to R₂₅ and the cycloalkyl group formed by Ztogether with the carbon atom may be monocyclic or polycyclic. Specificexamples thereof include a group having a monocyclo, bicyclo, tricycloor tetracyclo structure or the like with a carbon number of 5 or more.The carbon number thereof is preferably from 6 to 30, more preferablyfrom 7 to 25. These cycloalkyl groups each may have a substituent.

Preferred examples of the cycloalkyl group include an adamantyl group, anoradamantyl group, a decalin residue, a tricyclodecanyl group, atetracyclododecanyl group, a norbornyl group, a cedrol group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, a cyclodecanyl group and a cyclododecanyl group. Among these,more preferred are an adamantyl group, a norbornyl group, a cyclohexylgroup, a cyclopentyl group, a tetracyclododecanyl group and atricyclodecanyl group.

These alkyl group and cycloalkyl group each may further have asubstituent. Examples of the substituent which the alkyl group andcycloalkyl group may further have include an alkyl group (having acarbon number of 1 to 4), a halogen atom, a hydroxyl group, an alkoxygroup (having a carbon number of 1 to 4), a carboxyl group and analkoxycarbonyl group (having a carbon number of 2 to 6). These alkylgroup, alkoxy group, alkoxycarbonyl group and the like each may furtherhave a substituent. Examples of the substituent which the alkyl group,alkoxy group, alkoxycarbonyl group and the like may further have includea hydroxyl group, a halogen atom and an alkoxy group.

The structures represented by formulae (pI) to (pV) each can be used forthe protection of an alkali-soluble group in the resin. Examples of thealkali-soluble group include various groups known in this technicalfield.

Specific examples thereof include a structure where the hydrogen atom ofa carboxylic acid group, a sulfonic acid group, a phenol group or athiol group is replaced by the structure represented by any one offormulae (pI) to (pV). Among these, preferred is a structure where thehydrogen atom of a carboxylic acid group or a sulfonic acid group isreplaced by the structure represented by any one of formulae (pI) to(pV).

The repeating unit having an alkali-soluble group protected by thestructure represented by any one of formulae (pI) to (pV) is preferablya repeating unit represented by the following formula (pA):

In formula (pA), R represents a hydrogen atom, a halogen atom or alinear or branched alkyl group having a carbon number of 1 to 4, and aplurality of R's may be the same or different.

A represents a single bond, or sole group or a combination of two ormore groups, selected from the group consisting of an alkylene group, anether group, a thioether group, a carbonyl group, an ester group, anamido group, a sulfonamido group, a urethane group and a urea group. Ais preferably a single bond.

Rp₁ represents any one group of formulae (pI) to (pV).

The repeating unit represented by formula (pA) is most preferably arepeating unit comprising a 2-alkyl-2-adamantyl (meth)acrylate or adialkyl(1-adamantyl)methyl (meth)acrylate.

Specific examples of the repeating unit represented by formula (pA) areset forth below.

In the formulae above, Rx represents H, CH₃, CF₃ or CH₂OH, and Rxa andRxb each independently represents an alkyl group having a carbon numberof 1 to 4.

Examples of the halogen atom of R₁₁′ and R₁₂′ in formula (II-AB) includea chlorine atom, a bromine atom, a fluorine atom and an iodine atom.

The alkyl group of R₁₁′ and R₁₂′ is preferably a linear or branchedalkyl group having a carbon number of 1 to 10, and examples thereofinclude a methyl group, an ethyl group, an n-propyl group, an isopropylgroup and a linear or branched butyl, pentyl, hexyl or heptyl group.

The atomic group of Z′ for forming an alicyclic structure is an atomicgroup of forming, in the resin, an alicyclic hydrocarbon repeating unitwhich may have a substituent, and in particular, an atomic group offorming a crosslinked alicyclic structure to form a crosslinkedalicyclic hydrocarbon repeating unit is preferred.

Examples of the skeleton of the alicyclic hydrocarbon formed are thesame as those of the cycloalkyl group of R₁₂ to R₂₅ in formulae (pI) to(pVI).

The alicyclic hydrocarbon skeleton may have a substituent, and examplesof the substituent include R₁₃′ to R₁₆′ in formulae (II-AB1) and(II-AB2).

In the alicyclic hydrocarbon-based acid-decomposable resin for use inthe present invention, the group capable of decomposing under the actionof an acid may be contained in at least one repeating unit out of therepeating unit having an alicyclic hydrocarbon-containing partialstructure represented by any one of formulae (pI) to (pV), the repeatingunit represented by formula (II-AB), and the repeating unit comprising acopolymerization component described later.

Various substituents R₁₃′ to R₁₆′ in formulae (II-AB1) and (II-AB2) maywork out to a substituent of an atomic group for forming an alicyclicstructure in formula (II-AB) or an atomic group Z for forming acrosslinked alicyclic structure.

Specific examples of the repeating units represented by formulae(II-AB1) and (II-AB2) are set forth below, but the present invention isnot limited thereto.

The alicyclic hydrocarbon-based acid-decomposable resin for use in thepresent invention preferably has a repeating unit having a lactonegroup. As for the lactone group, any group may be used as long as it hasa lactone structure, but a group having a 5-, 6- or 7-membered ringlactone structure is preferred. The 5-, 6- or 7-membered ring lactonestructure is preferably condensed with another ring structure in theform of forming a bicyclo or spiro structure. The alicyclichydrocarbon-based acid-decomposable resin for use in the presentinvention more preferably has a repeating unit containing a group havinga lactone structure represented by any one of the following formulae(LC1-1) to (LC1-16). The group having a lactone structure may be bondeddirectly to the main chain. Among these lactone structures, (LC1-1),(LC1-4), (LC1-5), (LC1-6), (LC1-13) and (LC1-14) are preferred. Byvirtue of using a specific lactone structure, the line edge roughnessand the development defect are improved.

The lactone structure moiety may or may not have a substituent (Rb₂).Preferred examples of the substituent (Rb₂) include an alkyl grouphaving a carbon number of 1 to 8, a cycloalkyl group having a carbonnumber of 4 to 7, an alkoxy group having a carbon number of 1 to 8, analkoxycarbonyl group having a carbon number of 1 to 8, a carboxyl group,a halogen atom, a hydroxyl group, a cyano group and an acid-decomposablegroup. n₂ represents an integer of 0 to 4. When n₂ is an integer of 2 ormore, the plurality of Rb₂'s may be the same or different and also,Rb₂'s may combine with each other to form a ring.

Examples of the repeating unit containing a group having a lactonestructure represented by any one of formulae (LC1-1) to (LC1-16) includea repeating unit where at least one of R₁₃′ to R₁₆′ in formula (II-AB1)or (II-AB2) has a group represented by any one of formulae (LC1-1) to(LC1-16) (for example, R₅ of —COOR₅ is a group represented by any one offormulae (LC1-1) to (LC1-16)), and a repeating unit represented by thefollowing formula (AI):

In formula (AI), Rb₀ represents a hydrogen atom, a halogen atom or analkyl group having a carbon number of 1 to 4.

Examples of the alkyl group of Rb₀ include a methyl group, an ethylgroup, a propyl group, an n-butyl group, a sec-butyl group and atert-butyl group. The alkyl group of Rb₀ may have a substituent.Preferred examples of the substituent which the alkyl group of Rb₀ mayhave include a hydroxyl group and a halogen atom.

Examples of the halogen atom of Rb₀ include a fluorine atom, a chlorineatom, a bromine atom and an iodine atom. Rb₀ is preferably a hydrogenatom or a methyl group.

Ab represents an alkylene group, a divalent linking group having amonocyclic or polycyclic alicyclic hydrocarbon structure, a single bond,an ether group, an ester group, a carbonyl group, a carboxyl group, or adivalent group comprising a combination thereof, preferably a singlebond or a linking group represented by -Ab₁-CO₂—.

Ab₁ is a linear or branched alkylene group or a monocyclic or polycycliccycloalkylene group, preferably a methylene group, an ethylene group, acyclohexyl residue, an adamantyl residue or a norbornyl residue.

V represents a group represented by any one of formulae (LC1-1) to(LC1-16).

The repeating unit having a lactone structure usually has an opticalisomer, but any optical isomer may be used. One optical isomer may beused alone or a mixture of a plurality of optical isomers may be used.In the case of mainly using one optical isomer, the optical purity (ee)thereof is preferably 90 or more, more preferably 95 or more.

Specific examples of the repeating unit containing a group having alactone structure are set forth below, but the present invention is notlimited thereto.

(In formulae, Rx is H, CH₃, CH₂OH or CF₃.)

(In formulae, Rx is H, CH₃, CH₂OH or CF₃.)

(In formulae, Rx is H, CH₃, CH₂OH or CF₃.)

The alicyclic hydrocarbon-based acid-decomposable resin for use in thepresent invention preferably contains a repeating unit having analicyclic hydrocarbon structure substituted by a polar group. By virtueof this repeating unit, the adhesion to substrate and the affinity fordeveloper are enhanced. The polar group is preferably a hydroxyl groupor a cyano group.

Examples of the alicyclic hydrocarbon structure substituted by a polargroup include a structure represented by the following formula (VIIa) or(VIIb):

In formula (VIIa), R_(2c) to R_(4c) each independently represents ahydrogen atom, a hydroxyl group or a cyano group, provided that at leastone of R_(2c) to R_(4c) represents a hydroxyl group or a cyano group. Astructure where one or two member out of R_(2c) to R_(4c) is a hydroxylgroup with the remaining being a hydrogen atom is preferred, and astructure where two members out of R_(2c) to R_(4c) are a hydroxyl groupwith the remaining being a hydrogen atom is more preferred.

The group represented by formula (VIIa) is preferably a dihydroxy formor a monohydroxy form, more preferably a dihydroxy form.

Examples of the repeating unit having a group represented by formula(VIIa) or (VIIb) include a repeating unit where at least one of R₁₃′ toR₁₆′ in formula (II-AB1) or (II-AB2) has a group represented by formula(VIIa) or (VIIb) (for example, R₅ of —COOR₅ is a group represented byformula (VIIa) or (VIIb)), and a repeating unit represented by thefollowing formula (AIIa) or (AIIb):

In formulae (AIIa) and (AIIb), R_(1c) represents a hydrogen atom, amethyl group, a trifluoromethyl group or a hydroxymethyl group.

R_(2c) to R_(4c) have the same meanings as R₂ to R_(4c) in formula(VIIa).

Specific examples of the repeating unit having an alicyclic hydrocarbonstructure substituted by a polar group, represented by formula (AIIa) or(AIIb), are set forth below, but the present invention is not limitedthereto.

The alicyclic hydrocarbon-based acid-decomposable resin for use in thepresent invention may contain a repeating unit represented by thefollowing formula (VIII):

In formula (VIII), Z₂ represents —O— or —N(R₄₁)—. R₄₁ represents ahydrogen atom, a hydroxyl group, an alkyl group or —OSO₂—R₄₂. R₄₂represents an alkyl group, a cycloalkyl group or a camphor residue. Thealkyl group of R₄₁ and R₄₂ may be substituted by a halogen atom(preferably fluorine atom) or the like.

Specific examples of the repeating unit represented by formula (VIII)are set forth below, but the present invention is not limited thereto.

The alicyclic hydrocarbon-based acid-decomposable resin for use in thepresent invention preferably contains a repeating unit having analkali-soluble group, more preferably a repeating unit having a carboxylgroup. By virtue of containing such a repeating unit, the resolutionincreases in usage of forming contact holes. As for the repeating unithaving a carboxyl group, a repeating unit where a carboxyl group isdirectly bonded to the resin main chain, such as repeating unit by anacrylic acid or a methacrylic acid, and a repeating unit where acarboxyl group is bonded to the resin main chain through a linkinggroup, both are preferred. The linking group may have a monocyclic orpolycyclic hydrocarbon structure. An acrylic acid and a methacrylic acidare most preferred.

The alicyclic hydrocarbon-based acid-decomposable resin for use in thepresent invention may contain a repeating unit having from 1 to 3 groupsrepresented by the following formula (F1). By virtue of this repeatingunit, the line edge roughness performance is enhanced.

In formula (F1), R₅₀ to R₅₅ each independently represents a hydrogenatom, a fluorine atom or an alkyl group, provided that at least one ofR₅₀ to R₅₅ is a fluorine atom or an alkyl group with at least onehydrogen atom being substituted by a fluorine atom.

Rx represents a hydrogen atom or an organic group (preferably anacid-decomposable protective group, an alkyl group, a cycloalkyl group,an acyl group or an alkoxycarbonyl group).

The alkyl group of R₅₀ to R₅₅ may be substituted by a halogen atom(e.g., fluorine), a cyano group or the like, and is preferably an alkylgroup having a carbon number of 1 to 3, such as methyl group andtrifluoromethyl group.

It is preferred that R₅₀ to R₅₅ all are a fluorine atom.

The organic group represented by Rx is preferably an acid-decomposablegroup or an alkyl, cycloalkyl, acyl, alkylcarbonyl, alkoxycarbonyl,alkoxycarbonylmethyl, alkoxymethyl or 1-alkoxyethyl group which may havea substituent.

The repeating unit having a group represented by formula (F1) ispreferably a repeating unit represented by the following formula (F2):

In formula (F2), Rx represents a hydrogen atom, a halogen atom or analkyl group having a carbon number of 1 to 4. Preferred examples of thesubstituent which the alkyl group of Rx may have include a hydroxylgroup and a halogen atom.

Fa represents a single bond or a linear or branched alkylene group,preferably a single bond.

Fb represents a monocyclic or polycyclic hydrocarbon group.

Fc represents a single bond or a linear or branched alkylene group,preferably a single bond or a methylene group.

F₁ represents a group represented by formula (F1).

p₁ represents a number of 1 to 3.

The cyclic hydrocarbon group in Fb is preferably a cyclopentyl group, acyclohexyl group or a norbornyl group.

Specific examples of the repeating unit having a structure of formula(F1) are set forth below.

The alicyclic hydrocarbon-based acid-decomposable resin for use in thepresent invention may contain, in addition to the above-describedrepeating units, various repeating structural units for the purpose ofcontrolling the dry etching resistance, suitability for standarddeveloper, adhesion to substrate, resist profile and propertiesgenerally required of the resist, such as resolving power, heatresistance and sensitivity.

Examples of such a repeating structural unit include, but are notlimited to, repeating structural units corresponding to the monomersdescribed below.

By virtue of such a repeating structural unit, the performance requiredof the alicyclic hydrocarbon-based acid-decomposable resin,particularly,

(1) solubility in the coating solvent,

(2) film-forming property (glass transition point),

(3) alkali developability,

(4) film loss (selection of hydrophilic, hydrophobic or alkali-solublegroup),

(5) adhesion of unexposed area to substrate,

(6) dry etching resistance

and the like, can be subtly controlled.

Examples of such a monomer include a compound having oneaddition-polymerizable unsaturated bond selected from acrylic acidesters, methacrylic acid esters, acrylamides, methacrylamides, allylcompounds, vinyl ethers and vinyl esters.

Other than these, an addition-polymerizable unsaturated compoundcopolymerizable with the monomer corresponding to the above-describedvarious repeating structural units may be copolymerized.

In the alicyclic hydrocarbon-based acid-decomposable resin, the molarratio of respective repeating structural units contained isappropriately determined to control the dry etching resistance ofresist, suitability for standard developer, adhesion to substrate,resist profile and performances generally required of the resist, suchas resolving power, heat resistance and sensitivity.

The preferred embodiment of the alicyclic hydrocarbon-basedacid-decomposable resin for use in the present invention includes thefollowings:

(1) a resin containing a repeating unit having an alicyclichydrocarbon-containing partial structure represented by any one offormulae (pI) to (pV) (side chain type), preferably containing arepeating unit by a (meth)acrylate having a structure represented by anyone of formulae (pI) to (pV), and

(2) a resin containing a repeating unit represented by formula (II-AB)(main chain type).

The embodiment of (2) further includes:

(3) a resin having a repeating unit represented by formula (II-AB), amaleic anhydride derivative structure and a (meth)acrylate structure(hybrid type).

In the alicyclic hydrocarbon-based acid-decomposable resin, the contentof the repeating unit having an acid-decomposable group is preferablyfrom 10 to 60 mol %, more preferably from 20 to 50 mol %, still morepreferably from 25 to 40 mol %, based on all repeating structural units.

In the alicyclic hydrocarbon-based acid-decomposable resin, the contentof the repeating unit having an alicyclic hydrocarbon-containing partialstructure represented by any one of formulae (pI) to (pV) is preferablyfrom 25 to 70 mol %, more preferably from 35 to 65 mol %, still morepreferably from 40 to 60 mol %, based on all repeating structural units.

In the alicyclic hydrocarbon-based acid-decomposable resin, the contentof the repeating unit represented by formula (II-AB) is preferably from10 to 60 mol %, more preferably from 15 to 55 mol %, still morepreferably from 20 to 50 mol %, based on all repeating structural units.

In the resin, the content of the repeating structural unit based on themonomer as the further copolymerization component can also beappropriately selected according to the desired resist performance, butthe content thereof is preferably 99 mol % or less, more preferably 90mol % or less, still more preferably 80 mol % or less, based on thetotal molar number of the repeating structural unit having an alicyclichydrocarbon-containing partial structure represented by any one offormulae (pI) to (pV) and the repeating unit represented by formula(II-AB).

When the composition of the present invention is used for exposure withArF, the resin preferably has no aromatic group in view of transparencyto ArF light.

The alicyclic hydrocarbon-based acid-decomposable resin for use in thepresent invention is preferably a resin where all repeating unitscomprise a (meth)acrylate repeating unit. In this case, the repeatingunits may be all a methacrylate, all an acrylate, or a mixture ofmethacrylate/acrylate, but the content of the acrylate repeating unit ispreferably 50 mol % or less based on all repeating units.

The alicyclic hydrocarbon-based acid-decomposable resin for use in thepresent invention is more preferably a ternary copolymerization polymercomprising from 25 to 50% of the repeating unit having an alicyclichydrocarbon-containing partial structure represented by any one offormulae (pI) to (pV), from 25 to 50% of the repeating unit having alactone structure and from 5 to 30% of the repeating unit having analicyclic hydrocarbon structure substituted by a polar group, or aquaternary copolymerization polymer additionally comprising from 5 to20% of the repeating unit having a carboxyl group or a structurerepresented by formula (F1).

The alicyclic hydrocarbon-based acid-decomposable resin for use in thepresent invention can be synthesized by an ordinary method (for example,radical polymerization). Examples of the synthesis method in generalinclude a batch polymerization method of dissolving the monomer speciesand an initiator in a solvent and heating the solution, therebyeffecting the polymerization, and a dropping polymerization method ofadding dropwise a solution containing monomer species and an initiatorto a heated solvent over 1 to 10 hours. A dropping polymerization methodis preferred. Examples of the reaction solvent include tetrahydrofuran,1,4-dioxane, ethers (e.g., diisopropyl ether), ketones (e.g., methylethyl ketone, methyl isobutyl ketone), an ester solvent (e.g., ethylacetate), an amide solvent (e.g., dimethylformamide, diethylacetamide),and a solvent capable of dissolving the composition of the presentinvention, such as propylene glycol monomethyl ether acetate, propyleneglycol monomethyl ether and cyclohexanone which are described later. Thepolymerization is preferably performed by using the same solvent as thesolvent used in the photosensitive composition of the present invention.By the use of this solvent, generation of particles during storage canbe suppressed.

The polymerization reaction is preferably performed in an inert gasatmosphere such as nitrogen and argon. The polymerization is started byusing a commercially available radical initiator (e.g., azo-basedinitiator, peroxide). The radical initiator is preferably an azo-basedinitiator, and an azo-based initiator having an ester group, a cyanogroup or a carboxyl group is preferred. Preferred examples of theinitiator include azobisisobutyronitrile, azobisdimethylvaleronitrileand dimethyl 2,2′-azobis(2-methyl-propionate). The initiator is addedadditionally or in parts, if desired. After the completion of reaction,the reactant is charged into a solvent, and the desired polymer isrecovered by a method such as powder or solid recovery. The reactionconcentration is from 5 to 50 mass %, preferably from 10 to 30 mass %,and the reaction temperature is usually from 10 to 150° C., preferablyfrom 30 to 120° C., more preferably from 50 to 100° C.

In the case of using the composition of the present invention for theupper resist of a multilayer resist, the resin of the component (C)preferably has a silicon atom.

As for the resin having a silicon atom and capable of decomposing underthe action of an acid to increase the solubility in an alkali developer,a resin having a silicon atom at least in either the main chain or theside chain can be used. Examples of the resin having a siloxanestructure in the side chain of the resin include a copolymer of anolefin-based monomer having a silicon atom in the side chain and a(meth)acrylic acid-based monomer having a maleic anhydride and anacid-decomposable group in the side chain.

The resin having a silicon atom is preferably a resin having atrialkylsilyl structure or a monocyclic or polycyclic siloxanestructure, more preferably a resin containing a repeating unit having astructure represented by any one of the following formulae (SS-1) to(SS-4), still more preferably a resin containing a (meth)acrylic acidester-based, vinyl-based or acryl-based repeating unit having astructure represented by any one of formulae (SS-1) to (SS-4).

In formulae (SS-1) to (SS-4), Rs represents an alkyl group having acarbon number of 1 to 5, preferably a methyl group or an ethyl group.

The resin having a silicon atom is preferably a resin containing two ormore different repeating units having a silicon atom, more preferably aresin containing both (Sa) a repeating unit having from 1 to 4 siliconatoms and (Sb) a repeating unit having from 5 to 10 silicon atoms, stillmore preferably a resin containing at least one repeating unit having astructure represented by any one of formulae (SS-1) to (SS-3) and arepeating unit having a structure represented by formula (SS-4).

In the case of irradiating the positive photosensitive composition ofthe present invention with F₂ excimer laser light, the resin of thecomponent (C) is preferably a resin having a structure that a fluorineatom is substituted to the main chain and/or the side chain of thepolymer skeleton, and being capable of decomposing under the action ofan acid to increase the solubility in an alkali developer (hereinaftersometimes referred to as a “fluorine-based acid-decomposable resin”),more preferably a resin containing a hydroxyl group with the 1-positionbeing substituted by a fluorine atom or a fluoroalkyl group orcontaining a group where the hydroxyl group with the 1-position beingsubstituted by a fluorine atom or a fluoroalkyl group is protected by anacid-decomposable group, and still more preferably a resin having ahexafluoro-2-propanol structure or a structure that the hydroxyl groupof hexafluoro-2-propanol is protected by an acid-decomposable group. Byvirtue of introducing a fluorine atom, the transparency to farultraviolet light, particularly F₂ (157 nm) light, can be enhanced.

Preferred examples of the fluorine-based acid-decomposable resin includea resin having at least one repeating unit represented by the followingformulae (FA) to (FG):

In these formulae, R₁₀₀ to R₁₀₃ each represents a hydrogen atom, afluorine atom, an alkyl group or an aryl group.

R₁₀₄ and R₁₀₆ each is a hydrogen atom, a fluorine atom or an alkylgroup, and at least either one of R₁₀₄ and R₁₀₆ is a fluorine atom or afluoroalkyl group. R₁₀₄ and R₁₀₆ are preferably both a trifluoromethylgroup.

R₁₀₅ is a hydrogen atom, an alkyl group, a cycloalkyl group, an acylgroup, an alkoxycarbonyl group or a group capable of decomposing underthe action of an acid.

A₁ is a single bond, a divalent linking group such as alkylene group,cycloalkylene group, alkenylene group, arylene group, —COO—, —COO— and—CON(R₂₄)—, or a linking group comprising a plurality of members out ofthese groups. R₂₄ is a hydrogen atom or an alkyl group.

R₁₀₇ and R₁₀₈ each is a hydrogen atom, a halogen atom, an alkyl group,an alkoxy group, an alkoxycarbonyl group or a group capable ofdecomposing under the action of an acid.

R₁₀₉ is a hydrogen atom, an alkyl group, a cycloalkyl group or a groupcapable of decomposing under the action of an acid.

b is 0, 1 or 2.

In formulae (FA) and (FC), R₁₀₀ and R₁₀₁ may form a ring through analkylene group (having a carbon number of 1 to 5) which may besubstituted by fluorine.

The repeating units represented by formulae (FA) to (FG) each containsat least one fluorine atom, preferably 3 or more fluorine atoms, per onerepeating unit.

In formulae (FA) to (FG), the alkyl group is, for example, an alkylgroup having a carbon number of 1 to 8, and specific preferred examplesthereof include a methyl group, an ethyl group, a propyl group, ann-butyl group, a sec-butyl group, a hexyl group, a 2-ethylhexyl groupand an octyl group.

The cycloalkyl group may be monocyclic or polycyclic. The monocyclictype is a cycloalkyl group having a carbon number of 3 to 8, andpreferred examples thereof include a cyclopropyl group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group and a cyclooctyl group.The polycyclic type is a cycloalkyl group having a carbon number of 6 to20, and preferred examples thereof include an adamantyl group, anorbornyl group, an isoboronyl group, a camphanyl group, a dicyclopentylgroup, an α-pinel group, a tricyclodecanyl group, a tetracyclododecylgroup and an androstanyl group. In these monocyclic or polycycliccycloalkyl groups, the carbon atom may be substituted by a heteroatomsuch as oxygen atom.

The fluoroalkyl group is, for example, a fluoroalkyl group having acarbon number of 1 to 12, and specific preferred examples thereofinclude a trifluoromethyl group, a perfluoroethyl group, aperfluoropropyl group, a perfluorobutyl group, a perfluorohexyl group, aperfluorooctyl group, a perfluorooctylethyl group and a perfluorododecylgroup.

The aryl group is, for example, an aryl group having a carbon number of6 to 15, and specific preferred examples thereof include a phenyl group,a tolyl group, a dimethylphenyl group, a 2,4,6-trimethylphenyl group, anaphthyl group, an anthryl group and a 9,10-dimethoxyanthryl group.

The alkoxy group is, for example, an alkoxy group having a carbon numberof 1 to 8, and specific preferred examples thereof include a methoxygroup, an ethoxy group, an n-propoxy group, an iso-propoxy group, abutoxy group, a pentoxy group, an allyloxy group and an octoxy group.

The acyl group is, for example, an acyl group having a carbon number of1 to 10, and specific preferred examples thereof include a formyl group,an acetyl group, a propanoyl group, a butanoyl group, a pivaloyl group,an octanoyl group and a benzoyl group.

The alkoxycarbonyl group is preferably a secondary alkoxycarbonyl group,more preferably a tertiary alkoxycarbonyl group, such asi-propoxycarbonyl group, tert-butoxycarbonyl group, tert-amyloxycarbonylgroup and 1-methyl-1-cyclohexyloxycarbonyl group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

The alkylene group is preferably an alkylene group having a carbonnumber of 1 to 8, such as methylene group, ethylene group, propylenegroup, butylene group, hexylene group and octylene group.

The alkenylene group is preferably an alkenylene group having a carbonnumber of 2 to 6, such as ethenylene group, propenylene group andbutenylene group.

The cycloalkylene group is preferably a cycloalkylene group having acarbon number of 5 to 8, such as cyclopentylene group and cyclohexylenegroup.

The arylene group is preferably an arylene group having a carbon numberof 6 to 15, such as phenylene group, tolylene group and naphthylenegroup.

These groups each may have a substituent, and examples of thesubstituent include those having an active hydrogen, such as alkylgroup, cycloalkyl group, aryl group, amino group, amido group, ureidogroup, urethane group, hydroxyl group and carboxyl group, a halogen atom(e.g., fluorine, chlorine, bromine, iodine), an alkoxy group (e.g.,methoxy, ethoxy, propoxy, butoxy), a thioether group, an acyl group(e.g., acetyl, propanoyl, benzoyl), an acyloxy group (e.g., acetoxy,propanoyloxy, benzoyloxy), an alkoxycarbonyl group (e.g.,methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl), a cyano group and anitro group.

Here, the alkyl group, cycloalkyl group and aryl group include thosedescribed above, and the alkyl group may be further substituted by afluorine atom or a cycloalkyl group.

Examples of the group capable of decomposing under the action of an acidto show alkali solubility, which is contained in the fluorine-basedacid-decomposable resin of the present invention, include—O—C(R₃₆)(R₃₇)(R₃₈), —O—C(R₃₆)(R₃₇)(OR₃₉), —O—COO—C(R₃₆)(R₃₇)(R₃₈),—O—C(R₀₁)(R₀₂)COO—C(R₃₆)(R₃₇)(R₃₈), —COO—C(R₃₆)(R₃₇)(R₃₈) and—COO—C(R₃₆)(R₃₇)(OR₃₉).

R₃₆ to R₃₉ each represents an alkyl group, a cycloalkyl group, an arylgroup, an aralkyl group or an alkenyl group, and R₀₁ and R₀₂ eachrepresents a hydrogen atom, an alkyl group, a cycloalkyl group, analkenyl group (e.g., vinyl, allyl, butenyl, cyclohexenyl), an aralkylgroup (e.g., benzyl, phenethyl, naphthylmethyl) or an aryl group.

Specific preferred examples include an ether or ester group of atertiary alkyl group, such as tert-butyl group, tert-amyl group,1-alkyl-1-cyclohexyl group, 2-alkyl-2-adamantyl group,2-adamantyl-2-propyl group and 2-(4-methylcyclohexyl)-2-propyl group; anacetal or acetal ester group such as 1-alkoxy-1-ethoxy group andtetrahydropyranyl group; a tert-alkylcarbonate group; and atert-alkylcarbonylmethoxy group.

Specific examples of the repeating structural units represented byformulae (FA) to (FG) are set forth below, but the present invention isnot limited thereto.

The total content of the repeating units represented by formulae (FA) to(FG) is generally from 10 to 80 mol %, preferably from 30 to 70 mol %,more preferably from 35 to 65 mol %, based on all repeating unitsconstituting the resin.

In the fluorine-based acid-decomposable resin, in addition to theserepeating structural units, other polymerizable monomers may becopolymerized for the purpose of enhancing the performance of the resistof the present invention.

Examples of the copolymerization monomer which can be used include acompound having one addition-polymerizable unsaturated bond selectedfrom acrylic acid esters other than those described above, acrylamides,methacrylic acid esters, methacrylamides, allyl compounds, vinyl ethers,vinyl esters, styrenes and crotonic acid esters.

From the standpoint of enhancing the dry etching resistance, controllingthe alkali solubility and increasing the adhesion to substrate, thefluorine-based acid-decomposable resin preferably contains anotherrepeating unit as a copolymerization component in addition to theabove-described fluorine atom-containing repeating unit. Preferredexamples of the another repeating unit include:

1) a repeating unit having an alicyclic hydrocarbon structurerepresented by any one of formulae (pI) to (pVI) and formula (II-AB),specifically, repeating units 1 to 23 and repeating units [II-1] to[II-32], preferably repeating units 1 to 23 where Rx is CF₃;

2) a repeating unit having a lactone structure represented by formula(Lc) or by any one of formulae (V-1) to (V-5), specifically, repeatingunits shown above, particularly, repeating units having a grouprepresented by any one of formulae (Lc) and (V-1) to (V-4); and

3) a repeating unit derived from a maleic anhydride, a vinyl ether or avinyl compound having a cyano group, represented by the followingformula (XV), (XVI) or (XVII), specifically, repeating units (C-1) to(C-15). These repeating units each may or may not contain a fluorineatom.

In these formulae, R₄₁ represents an alkyl group, a cycloalkyl group, anaralkyl group or an aryl group, and the alkyl group of R₄₁ may besubstituted by an aryl group.

R₄₂ represents a hydrogen atom, a halogen atom, a cyano group or analkyl group.

A₅ represents a single bond, a divalent alkylene, alkenylene,cycloalkylene or arylene group, —O—CO—R₂₂, —OO—O—R₂₃— or—CO—N(R₂₄)—R₂₅—.

R₂₂, R₂₃ and R₂₅, which may be the same or different, each represents asingle bond or a divalent alkylene, alkenylene, cycloalkylene or arylenegroup which may have an ether group, an ester group, an amide group, aurethane group or a ureido group.

R₂₄ represents a hydrogen atom, an alkyl group, a cycloalkyl group, anaralkyl group or an aryl group.

Examples of each substituent are the same as those described above forthe substituents of formulae (FA) to (FG).

Specific examples of the repeating structural units represented byformulae (XV) to (XVII) are set forth below, but the present inventionis not limited thereto.

The total amount of the repeating unit represented by any one offormulae (XV) to (XVII) and the another repeating unit is generally from0 to 70 mol %, preferably from 10 to 60 mol %, more preferably from 20to 50 mol %, based on all repeating units constituting the resin.

The fluorine-based acid-decomposable resin may contain anacid-decomposable group in any repeating unit.

The content of the repeating unit having an acid-decomposable group ispreferably from 10 to 70 mol %, more preferably from 20 to 60 mol %,still more preferably from 30 to 60 mol %, based on all repeating units.

The fluorine-based acid-decomposable resin can be synthesized by radicalpolymerization almost in the same manner as the alicyclichydrocarbon-based acid-decomposable resin.

The weight average molecular weight of the resin as the component (C) ispreferably from 2,000 to 200,000 in terms of polystyrene by the GPCmethod. When the weight average molecular weight is 2,000 or more, heatresistance and dry etching resistance can be elevated and when theweight average molecular weight is 200,000 or less, developability canbe enhanced and at the same time, by virtue of reduction in theviscosity, the film-forming property can be enhanced. The molecularweight is more preferably from 5,000 to 50,000, still more preferablyfrom 7,000 to 30,000. By adjusting the molecular weight, the compositioncan be satisfied with all of heat resistance, resolving power,development defect and the like. The dispersity (Mw/Mn) of the resin asthe component (C) is preferably from 1.0 to 3.0, more preferably from1.2 to 2.5, still more preferably from 1.2 to 1.6. By adjusting thedispersity to an appropriate range, the line edge roughness performancecan be enhanced.

In the positive photosensitive composition of the present invention, theamount of the resin as the component (C) blended in the entirecomposition is preferably from 40 to 99.99 mass %, more preferably from50 to 99 mass %, still more preferably from 80 to 96 mass %, based onthe entire solid content.

[4] (D) Dissolution Inhibiting Compound Capable of Decomposing Under theAction of an Acid to Increase the Solubility in an Alkali Developer andHaving a Molecular Weight of 3,000 or Less (Hereinafter SometimesReferred to as a “Component (D)” or “Dissolution Inhibiting Compound”)

In order to prevent reduction in the transparency to light at 220 nm orless, the dissolution inhibiting compound (D) capable of decomposingunder the action of an acid to increase the solubility in an alkalideveloper and having a molecular weight of 3,000 or less is preferablyan alicyclic or aliphatic compound containing an acid-decomposablegroup, such as acid-decomposable group-containing cholic acid derivativedescribed in Proceeding of SPIE, 2724, 355 (1996). Examples of theacid-decomposable group and alicyclic structure are the same as thosedescribed above for the alicyclic hydrocarbon-based acid-decomposableresin.

In the case where the photosensitive composition of the presentinvention is exposed with a KrF excimer laser or irradiated withelectron beams, the dissolution inhibiting compound preferably containsa structure in which the phenolic hydroxyl group of a phenol compound isreplaced by an acid-decomposable group. The phenol compound ispreferably a phenol compound containing from 1 to 9 phenol skeletons,more preferably from 2 to 6 phenol skeletons.

The molecular weight of the dissolution inhibiting compound for use inthe present invention is 3,000 or less, preferably from 300 to 3,000,more preferably from 500 to 2,500.

The amount of the dissolution inhibiting compound added is preferablyfrom 3 to 50 mass %, more preferably from 5 to 40 mass %, based on thesolid content of the photosensitive composition.

Specific examples of the dissolution inhibiting compound are set forthbelow, but the present invention is not limited thereto.

[5] (E) Resin Soluble in an Alkali Developer (Hereinafter SometimesReferred to as a “Component (E)” or “Alkali-Soluble Resin”)

The alkali dissolution rate of the alkali-soluble resin is preferably 20Å/sec or more, more preferably 200 Å/sec or more (Å is angstrom), asmeasured (at 23° C.) in 0.261N tetramethylammonium hydroxide (TMAH).

Examples of the alkali-soluble resin for use in the present inventioninclude, but are not limited to, novolak resin, hydrogenated novolakresin, acetone-pyrogallol resin, o-polyhydroxystyrene,m-polyhydroxystyrene, p-polyhydroxystyrene, hydrogenatedpolyhydroxystyrene, halogen- or alkyl-substituted polyhydroxystyrene, ahydroxystyrene-N-substituted maleimide copolymer, an o/p- orm/p-hydroxystyrene copolymer, polyhydroxystyrene with the hydroxyl groupbeing partially O-alkylated (for example, 5 to 30 mol % beingO-methylated, O-(1-methoxy)ethylated, O-(1-ethoxy)ethylated,O-2-tetrahydropyranylated or O-(tert-butoxycarbonyl)methylated) orO-acylated (for example, 5 to 30 mol % being o-acylated orO-(tert-butoxy)carbonylated), a styrene-maleic anhydride copolymer, astyrene-hydroxystyrene copolymer, an α-methylstyrene-hydroxystyrenecopolymer, a carboxyl group-containing methacrylic resin including aderivative thereof, and a polyvinyl alcohol derivative.

Among these alkali-soluble resins, preferred are novolak resin,o-polyhydroxystyrene, m-polyhydroxystyrene, p-polyhydroxystyrene, acopolymer thereof, alkyl-substituted polyhydroxystyrene, partiallyO-alkylated or O-acylated polyhydroxystyrene, a styrene-hydroxystyrenecopolymer, and an α-methylstyrene-hydroxystyrene copolymer.

The novolak resin can be obtained by subjecting a predetermined monomeras the main component to addition condensation with aldehydes in thepresence of an acidic catalyst.

The weight average molecular weight of the alkali-soluble resin is 2,000or more, preferably from 5,000 to 200,000, more preferably from 5,000 to100,000.

The weight average molecular weight used herein is defined as apolystyrene-reduced value measured by gel permeation chromatography.

In the present invention, two or more kinds of these alkali-solubleresins (E) may be used in combination.

The amount of the alkali-soluble resin used is from 40 to 97 mass %,preferably from 60 to 90 mass %, based on the entire solid content ofthe photosensitive composition.

[6] (F) Acid Crosslinking Agent Capable of Crosslinking with theAlkali-Soluble Resin Under the Action of an Acid (Hereinafter SometimesReferred to as a “Component (F)” or “Crosslinking Agent”)

In the negative photosensitive composition of the present invention, acrosslinking agent is used.

The crosslinking agent may be any compound as long as it causescrosslinking of the resin soluble in an alkali developer under theaction of an acid, but the following compounds (1) to (3) are preferred:

(1) a hydroxymethyl, alkoxymethyl or acyloxymethyl form of a phenolderivative,

(2) a compound having an N-hydroxymethyl group, an N-alkoxymethyl groupor an N-acyloxymethyl group, and

(3) a compound having an epoxy group.

The alkoxymethyl group is preferably an alkoxymethyl group having acarbon number of 6 or less, and the acyloxymethyl group is preferably anacyloxymethyl group having a carbon number of 6 or less.

Among these crosslinking agents, the followings are particularlypreferred.

In these formulae, L¹ to L⁸, which may be the same or different, eachrepresents a hydrogen atom, a hydroxymethyl group, a methoxymethylgroup, an ethoxymethyl group or an alkyl group having a carbon number of1 to 6.

The crosslinking agent is usually added in an amount of 3 to 70 mass %,preferably from 5 to 50 mass %, based on the solid content of thephotosensitive composition.

<Other Components>

[7] (G) Basic Compound

The photosensitive composition of the present invention preferablycontains (G) a basic compound so as to reduce the change of performancein aging from exposure to heating.

Preferred structures of the basic compound include structuresrepresented by the following formulae (A) to (E).

In these formulae, R²⁵⁰, R²⁵¹ and R²⁵² each independently represents ahydrogen atom, an alkyl group having a carbon number of 1 to 20, acycloalkyl group having a carbon number of 3 to 20, or an aryl grouphaving a carbon number of 6 to 20, and R²⁵⁰ and R²⁵¹ may combine witheach other to form a ring. These groups each may have a substituent. Thealkyl or cycloalkyl group having a substituent is preferably anaminoalkyl group having a carbon number of 1 to 20, an aminocycloalkylgroup having a carbon number of 3 to 20, a hydroxyalkyl group having acarbon number of 1 to 20, or a hydroxycycloalkyl group having a carbonnumber of 3 to 20.

These groups each may contain an oxygen atom, a sulfur atom or anitrogen atom in the alkyl chain.

R²⁵³, R²⁵⁴, R²⁵⁵ and R²⁵⁶ each independently represents an alkyl grouphaving a carbon number of 1 to 6 or a cycloalkyl group having a carbonnumber of 3 to 6.

Preferred examples of the compound include guanidine, aminopyrrolidine,pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholineand piperidine, and these compound each may have a substituent. Thecompound is more preferably, for example, a compound having an imidazolestructure, a diazabicyclo structure, an onium hydroxide structure, anonium carboxylate structure, a trialkylamine structure, an anilinestructure or a pyridine structure; an alkylamine derivative having ahydroxyl group and/or an ether bond; or an aniline derivative having ahydroxyl group and/or an ether bond.

Examples of the compound having an imidazole structure includeimidazole, 2,4,5-triphenylimidazole and benzimidazole. Examples of thecompound having a diazabicyclo structure include1,4-diazabicyclo[2,2,2]octane, 1,5-diazabicyclo[4,3,0]non-5-ene and1,8-diazabicyclo[5,4,0]undec-7-ene. Examples of the compound having anonium hydroxide structure include a triarylsulfonium hydroxide, aphenacylsulfonium hydroxide and a sulfonium hydroxide having a2-oxoalkyl group, specifically, triphenylsulfonium hydroxide,tris(tert-butylphenyl)sulfonium hydroxide, bis(tert-butylphenyl)iodoniumhydroxide, phenacylthiophenium hydroxide and 2-oxopropylthiopheniumhydroxide. The compound having an onium carboxylate structure is acompound where the anion moiety of the compound having an oniumhydroxide structure is converted into a carboxylate, and examplesthereof include acetate, adamantane-1-carboxylate and perfluoroalkylcarboxylate. Examples of the compound having a trialkylamine structureinclude tri(n-butyl)amine and tri(n-octyl)amine. Examples of the anilinecompound include 2,6-diisopropylaniline and N,N-dimethylaniline.Examples of the alkylamine derivative having a hydroxyl group and/or anether bond include ethanolamine, diethanolamine, triethanolamine andtris-(methoxyethoxyethyl)amine. Examples of the aniline derivativehaving a hydroxyl group and/or an ether bond includeN,N-bis(hydroxyethyl)aniline.

One of these basic compounds may be used alone, or two or more thereofmay be used in combination. However, when the amount of the component(B) used is 0.05 mass % or more, the basic substance may or may not beused. In the case of using the basic compound, the amount used thereofis usually from 0.001 to 10 mass %, preferably from 0.01 to 5 mass %,based on the solid content of the photosensitive composition. The amountused is preferably 0.001 mass % or more for obtaining a sufficientlyhigh addition effect and preferably 10 mass % or less in view ofsensitivity and developability of unexposed area.

[8] (H) Fluorine- and/or Silicon-Containing Surfactant

The photosensitive composition of the present invention preferablyfurther contains any one fluorine- and/or silicon-containing surfactant(a fluorine-containing surfactant, a silicon-containing surfactant or asurfactant containing both a fluorine atom and a silicon atom), or twoor more thereof.

When the photosensitive composition of the present invention contains afluorine- and/or silicon-containing surfactant, a resist pattern withgood sensitivity, resolution and adhesion and less development defectscan be obtained at the time of using an exposure light source of 250 nmor less, particularly 220 nm or less.

Examples of the fluorine- and/or silicon-containing surfactant includesurfactants described in JP-A-62-36663, JP-A-61-226746, JP-A-61-226745,JP-A-62-170950, JP-A-63-34540, JP-A-7-230165, JP-A-8-62834,JP-A-9-54432, JP-A-9-5988, JP-A-2002-277862 and U.S. Pat. Nos.5,405,720, 5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143,5,294,511 and 5,824,451. The following commercially availablesurfactants each may also be used as it is.

Examples of the commercially available surfactant which can be usedinclude a fluorine-containing surfactant and a silicon-containingsurfactant, such as EFtop EF301 and EF303 (produced by Shin-Akita KaseiK.K.), Florad FC430 and 431 (produced by Sumitomo 3M Inc.), MegafacF171, F173, F176, F189 and R⁰⁸ (produced by Dainippon Ink & Chemicals,Inc.), Surflon S-382, SC101, 102, 103, 104, 105 and 106 (produced byAsahi Glass Co., Ltd.), and Troysol S-366 (produced by Troy Chemical).In addition, polysiloxane polymer KP-341 (produced by Shin-Etsu ChemicalCo., Ltd.) may also be used as the silicon-containing surfactant.

Other than these known surfactants, a surfactant using a polymer havinga fluoro-aliphatic group, which is derived from a fluoro-aliphaticcompound produced by telomerization process (also called telomerprocess) or oligomerization process (also called oligomer process), maybe used. The fluoro-aliphatic compound can be synthesized by the methoddescribed in JP-A-2002-90991.

The polymer having a fluoro-aliphatic group is preferably a copolymer ofa fluoro-aliphatic group-containing monomer with (poly(oxyalkylene))acrylate and/or (poly(oxyalkylene)) methacrylate, and the polymer mayhave an irregular distribution or may be a block copolymer. Examples ofthe poly(oxyalkylene) group include a poly(oxy-ethylene) group, apoly(oxypropylene) group and a poly(oxybutylene group). This group mayalso be a unit having alkylenes differing in the chain length within thesame chain, such as block-linked poly(oxyethylene, oxypropylene andoxyethylene) and block-linked poly(oxyethylene and oxypropylene).Furthermore, the copolymer of a fluoro-aliphatic group-containingmonomer and a (poly(oxyalkylene)) acrylate (or methacrylate) may be notonly a binary copolymer but also a ternary or greater copolymer obtainedby simultaneously copolymerizing two or more different fluoro-aliphaticgroup-containing monomers or two or more different (poly(oxyalkylene))acrylates (or methacrylates).

Examples thereof include commercially available surfactants such asMegafac F178, F-470, F-473, F-475, F-476 and F-472 (produced byDainippon Ink & Chemicals, Inc.). Other examples include a copolymer ofan acrylate (or methacrylate) having a C₆F₁₃ group with a(poly(oxyalkylene)) acrylate (or methacrylate), a copolymer of anacrylate (or methacrylate) having a C₆F₁₃ group with a(poly(oxyethylene)) acrylate (or methacrylate) and a(poly(oxypropylene)) acrylate (or methacrylate), a copolymer of anacrylate (or methacrylate) having a C₈F₁₇ group with a(poly(oxyalkylene)) acrylate (or methacrylate), and a copolymer of anacrylate (or methacrylate) having a C₈F₁₇ group with a(poly(oxyethylene)) acrylate (or methacrylate) and a(poly(oxypropylene)) acrylate (or methacrylate).

The amount of the fluorine- and/or silicon-containing surfactant used ispreferably from 0.0001 to 2 mass %, more preferably from 0.001 to 1 mass%, based on the entire amount of the photosensitive composition(excluding the solvent).

[9] (I) Organic Solvent

The photosensitive composition of the present invention is used bydissolving the above-described components in a predetermined organicsolvent.

Examples of the organic solvent which can be used include ethylenedichloride, cyclohexanone, cyclopentanone, 2-heptanone, γ-butyrolactone,methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, 2-methoxyethyl acetate, ethylene glycol monoethyl etheracetate, propylene glycol monomethyl ether, propylene glycol monomethylether acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate,methyl methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethylpyruvate, propyl pyruvate, N,N-dimethylformamide, dimethylsulfoxide,N-methylpyrrolidone and tetrahydrofuran.

(Ia) Ketone-Based Solvent

The solvent for use in the present invention is preferably a solventhaving at least one ketone structure.

The solvent having a ketone structure includes a chain ketone solventand a cyclic ketone solvent. A compound having a total carbon number of5 to 8 is preferred in view of good coatability.

Examples of the chain ketone solvent include 2-heptanone, methyl ethylketone and methyl isobutyl ketone, with 2-heptanone being preferred.

Examples of the cyclic ketone solvent include cyclopentanone,3-methyl-2-cyclopentanone, cyclohexanone, 2-methylcyclohexanone,2,6-dimethylcyclohexanone, cyclo-heptanone, cyclooctanone andisophorone, with cyclohexanone and cycloheptanone being preferred.

The solvent is preferably used as sole solvent having a ketone structureor as a mixed solvent with another solvent. Examples of the solventmixed (solvent used in combination) include a propylene glycol monoalkylether carboxylate, an alkyl lactate, a propylene glycol monoalkyl ether,an alkyl alkoxypropionate and a lactone compound.

Examples of the propylene glycol monoalkyl ether carboxylate includepropylene glycol monomethyl ether acetate, propylene glycol monomethylether propionate and propylene glycol monoethyl ether acetate.

Examples of the alkyl lactate include methyl lactate and ethyl lactate.

Examples of the propylene glycol monoalkyl ether include propyleneglycol monomethyl ether and propylene glycol monoethyl ether.

Examples of the alkyl alkoxypropionate include methyl methoxypropionate,ethyl methoxypropionate, methyl ethoxypropionate and ethylethoxypropionate.

Examples of the lactone compound include γ-butyrolactone.

The solvent used in combination is preferably a propylene glycolmonoalkyl ether carboxylate, an alkyl lactate or a propylene glycolmonoalkyl ether, more preferably propylene glycol monomethyl etheracetate.

By virtue of mixing the ketone-based solvent and the solvent used incombination, adhesion to substrate, developability, DOF and the like areimproved.

The ratio (by mass) of the ketone-based solvent and the solvent used incombination is preferably from 10/90 to 95/5, more preferably from 20/80to 80/20, still more preferably from 30/70 to 70/30.

From the standpoint of enhancing the film thickness uniformity ordevelopment defect performance, a high boiling point solvent having aboiling point of 200° C. or more, such as ethylene carbonate andpropylene carbonate, may be mixed.

The amount of the high boiling point solvent added is usually from 0.1to 15 mass %, preferably from 0.5 to 10 mass %, more preferably from 1to 5 mass %, based on the entire solvent.

In the present invention, a photosensitive composition having a solidcontent concentration of usually from 3 to 25 mass %, preferably from 5to 22 mass %, more preferably from 5 to 15 mass %, is prepared by usinga solvent alone, preferably by using two or more kinds of solvents.

<Other Additives>

If desired, the photosensitive composition of the present invention mayfurther contain, for example, a dye, a plasticizer, a surfactant otherthan the component (H), a photosensitizer, and a compound capable ofaccelerating the solubility in a developer.

The compound capable of accelerating the dissolution in a developer,which can be used in the present invention, is a low molecular compoundcontaining two or more phenolic OH groups or one or more carboxy groupand having a molecular weight of 1,000 or less. In the case ofcontaining a carboxyl group, an alicyclic or aliphatic compound ispreferred.

The amount of the dissolution accelerating compound added is preferablyfrom 2 to 50 mass %, more preferably from 5 to 30 mass %, based on theresin of component (C) or the resin of component (E). The amount addedis preferably 50 mass % or less from the standpoint of suppressing thedevelopment residue or preventing the deformation of pattern at thedevelopment.

The phenol compound having a molecular weight of 1,000 or less can beeasily synthesized by one skilled in the art by referring to the methoddescribed, for example, in JP-A-4-122938, JP-A-2-28531, U.S. Pat. No.4,916,210 and European Patent 219294.

Specific examples of the alicyclic or aliphatic compound having acarboxy group include, but are not limited to, a carboxylic acidderivative having a steroid structure, such as cholic acid, deoxycholicacid and lithocholic acid, an adamantane carboxylic acid derivative, anadamantane dicarboxylic acid, a cyclohexanecarboxylic acid and acyclohexanedicarboxylic acid.

In the present invention, a surfactant other than the fluorine- and/orsilicon-containing surfactant (H) can also be added. Specific examplesthereof include a nonionic surfactant such as polyoxyethylene alkylethers, polyoxyethylene alkylallyl ethers,polyoxyethylene.polyoxypropylene block copolymers, sorbitan fatty acidesters and polyoxyethylene sorbitan fatty acid esters.

One of these surfactants may be used alone or some of these surfactantsmay be used in combination.

(Pattern Forming Method)

The photosensitive composition of the present invention is used bydissolving the above-described components in a predetermined organicsolvent, preferably a mixed solvent described above, and coating theobtained solution on a predetermined support as follows.

For example, the photosensitive composition is coated on a substrate(e.g., silicon/silicon dioxide-coated substrate) as used in theproduction of a precision integrated circuit device, by an appropriatecoating method such as spinner or coater, and dried to form aphotosensitive film.

This photosensitive film is irradiated with actinic rays or radiationthrough a predetermined mask, preferably subjected to baking (heating),and then developed, whereby a good pattern can be obtained.

At the irradiation with actinic rays or radiation, the exposure may beperformed by filling a liquid having a refractive index higher than thatof air between the photosensitive film and the lens (immersionexposure). By this exposure, resolution can be elevated.

Examples of the actinic ray or radiation include infrared light, visiblelight, ultraviolet light, far ultraviolet light, X-ray and electronbeam. Among these, preferred is far ultraviolet light at a wavelength of250 nm or less, more preferably 220 nm or less. Specifically, a KrFexcimer laser (248 nm), an ArF excimer laser (193 nm), an F₂ excimerlaser (157 nm), an X-ray, an electron beam and the like are used. An ArFexcimer laser, an F₂ excimer laser, EUV (13 nm) and an electron beam arepreferred.

In the development step, an alkali developer is used as follows. Thealkali developer usable for the resist composition is an alkalineaqueous solution of inorganic alkalis such as sodium hydroxide,potassium hydroxide, sodium carbonate, sodium silicate, sodiummetasilicate and aqueous ammonia, primary amines such as ethylamine andn-propylamine, secondary amines such as diethylamine anddi-n-butylamine, tertiary amines such as triethylamine andmethyldiethylamine, alcohol amines such as dimethylethanolamine andtriethanolamine, a quaternary ammonium salt such as tetramethylammoniumhydroxide and tetraethylammonium hydroxide, or cyclic amines such aspyrrole and piperidine.

In the alkali developer, alcohols and a surfactant may also be added inan appropriate amount.

The alkali concentration of the alkali developer is usually from 0.1 to20 mass %. The pH of the alkali developer is usually from 10.0 to 15.0.

EXAMPLES

The present invention is described in greater detail below by referringto Examples, but the present invention should not be construed as beinglimited thereto.

Synthesis Example of Compound (A) Synthesis Example 1 Synthesis ofCompound (A-1)

In a 1,000 mL-volume three-neck flask equipped with a 100-mL droppingfunnel and a nitrogen inlet tube, 34.4 g (200 mmol) of sulfanylamide wascharged and then dissolved in 200 mL of 10% NaOH, and the resultingsolution was stirred under ice cooling. Subsequently, 55.3 g (200 mmol)of 1-octanesulfonyl chloride was added dropwise through the droppingfunnel over 1 hour. After the dropwise addition, the mixed solution wasstirred under ice cooling for 1 hour and after removing the ice bath,further stirred at room temperature for 3 hours. Thereafter,concentrated hydrochloric acid was added dropwise to the reactionsolution, thereby effecting neutralization, and the precipitated whitesolid was filtered. This solid was then recrystallized fromwater/methanol to obtain 45.1 g of the following compound as aplate-like crystal.

Separately, 16.1 g (46.9 mmol) of triphenylsulfonium bromide and 12.4 g(53.5 mmol) of silver oxide were added to 150 mL of methanol, and theresulting mixture was stirred at room temperature for 2 hours. Afterremoving the silver salt by filtration, 16.34 g (46.9 mmol) of thecompound prepared above was added to the filtrate, and this solution wasfurther stirred for 1 hour. Subsequently, the solvent was removed andafter adding 200 mL of chloroform to the residue, the organic layer waswashed with water. Furthermore, the solvent was removed, and the residuewas dried to obtain 20.9 g of Compound (A-1) as a white solid.

¹H-NMR (400 MHz, CD₃OD):

δ 0.93 (t, 3H), 1.34-1.46 (m, 10H), 1.81 (quin, 2H), 3.24 (t, 2H), 6.78(d, 2H), 7.66-7.78 (m, 17H).

Synthesis Example 2 Synthesis of Compound (A-6)

Triphenylsulfonium bromide (8.01 g (23.34 mmol)) and 5.68 g (24.51 mmol)were added to 100 mL of methanol, and the resulting mixture was stirredat room temperature for 2 hours. After removing the silver salt byfiltration, 5.0 g (23.34 mmol) sulfacetamide was added to the filtrate,and this solution was further stirred for 1 hour. Thereafter, thesolvent was removed, and the residue was dried to obtain 10.0 g ofCompound (A-6) as a white solid.

¹H-NMR (400 MHz, CD₃OD):

δ 1.84 (s, 3H), 6.63 (d, 2H), 7.63 (d, 2H), 7.78-7.87 (m, 15H).

Synthesis Example 3 Synthesis of Compound (A-8)

In a nitrogen stream, a mixture containing 5.0 g (15.8 mmol) of1,1,2,2,3,3-hexafluoropropane-1,3-disulfonyl difluoride and 50 mL of THFwas ice-cooled and thereto, a mixed solution containing 1.66 g (16.6mmol) of 1-methylpiperazine, 10 mL of triethylamine and 50 mL of THF wasadded dropwise over 60 minutes. The resulting solution was stirred underice cooling for 1 hour and further stirred at room temperature for 1hour. Thereafter, the organic layer was washed with water, an aqueoussaturated ammonium chloride solution and water in this order and thendried over sodium sulfate. After concentrating the solvent, 2.36 g (15.8mmol) of trifluoromethanesulfonamide and 10 mL of triethylamine wereadded to the residue, and this mixture was transferred to apressure-resistant glass tube and stirred at 100° C. for 20 hours in thesealed tube. Subsequently, 100 mL of chloroform was added, and theorganic layer was washed with water and then dried over sodium sulfateto obtain a brown oil. This oil was then rendered neutral by addingthereto 25 mL of methanol and 60 mL of 1.5N—HCl, and the precipitatedwhite solid was filtered to obtain 5.65 g of the following compound.

The compound (4.0 g) obtained above was dissolved in a mixed solventcontaining 100 ml of methanol and 40 ml of 1M-NaOH and after adding 2.61g (7.61 mmol) of triphenylsulfonium bromide, the resulting solution wasstirred at room temperature for 3 hours. Subsequently, 200 mL ofchloroform was added, the organic layer was washed with water, thesolvent was removed, and the residue was purified by columnchromatography (SiO₂, chloroform/methanol=10/1) to obtain the objectiveCompound (A-8) (4.56 g) as a white solid.

¹H-NMR (400 MHz, CDCl₃):

δ 2.32 (s, 3H), 2.50 (m, 4H), 3.55 (m, 4H), 7.65-7.80 (m, 15H).

¹⁹F-NMR (400 MHz, CDCl₃):

δ-118.5 (m, 2F), −112.3 (m, 2F), −111.1 (m, 2F), −78.6 (m, 3F).

Other compounds (A) were synthesized in the same manner.

<Resin (C)>

The structure, molecular weight and dispersity of the resin (C) used inExamples are shown below.

Examples 1 to 17 and Comparative Examples 1 to 3 Preparation of Resist

The components shown in Table 1 below were dissolved in a solvent toprepare a solution having a solid content concentration of 12 mass %,and this solution was filtered through a 0.1-μm polytetrafluoroethylenefilter or polyethylene filter to prepare a positive resist solution. Thepositive resist solution prepared was evaluated by the followingmethods. The results obtained are shown in Table 1.

<Evaluation of Resist>

An antireflection film DUV-42 produced by Brewer Science Co., Ltd. wasuniformly coated on a silicon substrate treated withhexamethyldisilazane by a spin coater to a thickness of 600 Å, dried ona hot plate at 100° C. for 90 seconds and then dried under heating at190° C. for 240 seconds. Thereafter, each positive resist solution wascoated by a spin coater and dried at 120° C. for 90 seconds to form aresist film of 0.25 μm.

The formed resist film was exposed by an ArF excimer laser stepper(manufactured by ISI, NA=0.6) through a mask and immediately after theexposure, heated on a hot plate at 120° C. for 90 seconds. Furthermore,the resist film was developed with an aqueous 2.38 mass %tetramethylammonium hydroxide solution at 23° C. for 60 seconds, rinsedwith pure water for 30 seconds and dried to obtain a line pattern.

Defocus Latitude Depended on Line Pitch:

The line width of an isolated pattern (line/space=1/10) at the exposureamount for reproducing a mask pattern of a 130-nm dense pattern(line/space=1/1) was evaluated and expressed by the difference (nm) from130 nm. As the value is smaller, the difference in performance betweenthe dense pattern and the isolated pattern is smaller and the defocuslatitude depended on line pitch is better.

Line Edge Roughness:

In the measurement of line edge roughness, a 90-nm pattern was observedby using a length-measuring scanning electron microscope (SEM). Withrespect to the region where the edge in the longitudinal direction ofthe line pattern was 5 μm, the distance from a reference line where theedge should be present was measured at 50 points by a length-measuringSEM (S-8840, manufactured by Hitachi, Ltd.) and after determining thestandard deviation, 3σ was calculated. As the value is smaller, theperformance is better.

Pattern Profile:

Assuming that the exposure amount for reproducing a line-and-space maskpattern with a line width of 90 nm is an optimal exposure amount, theprofile at the optimal exposure amount was observed by a scanningelectron microscope (SEM).

TABLE 1 ArF, Positive Compound Surfactant (A) (g) Acid Generator (g)Resin (10 g) Basic Compound (g) (0.03 g) Example  1 A-1 (0.2) z38 (0.3)RA-1 PEA/TPA (0.01/0.02) W-4  2 A-6 (0.2) z60 (0.4) RA-20 PEA/DIA(0.01/0.02) W-4 z38 (0.5)  3 A-3 (0.2) z63 (0.4) RA-22 PEA (0.02) W-4  4A-14 (0.3) z58 (0.4) RA-21 PEA/DIA (0.01/0.02) W-4  5 A-5 (0.3) z57(0.3) RA-19 PEA (0.02) W-4  6 A-8 (0.2) z61 (0.4) RA-21 PEA/DIA(0.02/0.02) W-1  7 A-7 (0.2) z50 (0.4) RA-24 DIA (0.02) W-2  8 A-8 (0.2)z58 (0.3) RA-7 PEA (0.02) W-4  9 A-11 (0.2) z38 (0.5) RA-8 PEA (0.02)W-2 10 A-20 (0.3) z59 (0.3) RA-20 DIA (0.02) W-4 11 A-8 (0.2) z58 (0.4)RA-22 PEA (0.02) W-4 z60 (0.3) 12 A-33 (0.1) z60 (0.4) RA-21 PEA (0.03)W-2 13 A-38 (0.2) z61 (0.5) RA-20 PEA (0.03) W-4 14 A-42  (0.18) z63(0.3) RA-8 PEA/DIA (0.01/0.01) W-4 15 A-44 (0.2) z38 (0.3) RA-25 PEA(0.03) W-4 16 A-2 (0.1) z58 (0.3) RA-4 TMEA (0.02) W-4 17 A-28 (0.3) z38(0.5) RA-23 DIA (0.02) W-1 Comparative Example  1 none (—) z38 (0.4)RA-6 DIA (0.02) W-4  2 none (—) z38 (0.4) RA-20 PEA/DIA (0.01/0.02) W-4 3 none (—) z38 (0.3) RA-7 TMEA (0.03) W-4 Defocus Latitude DissolutionInhibiting Depended on Line Pitch Line Edge Roughness Solvent (ratio bymass) Compound (g) (nm) (nm) Pattern Profile Example  1 A1/B1 (60/40)21.0 4.2 slightly tapered  2 A1/B1 (70/30) 23.7 3.6 slightly tapered  3A1/A3 (60/40) LCB (0.2) 20.6 4.1 slightly tapered  4 A1/A3 (60/40) 21.04.6 rectangular  5 A1/B1 (80/20) 21.3 3.3 slightly tapered  6 A1/B1(80/20) 25.3 3.9 slightly tapered  7 A1/B1 (60/40) 18.9 3.7 slightlytapered  8 A1/A3 (80/20) 21.1 4.0 slightly tapered  9 A1/B1 (60/40) 21.93.5 rectangular 10 A1/A4 (60/40) 20.6 3.9 slightly tapered 11 A1/B1(60/40) LCB (0.5) 23.1 3.5 slightly tapered 12 A1/B2 (60/40) 21.1 4.0rectangular 13 A1/B1 (80/20) 26.9 3.5 slightly tapered 14 A1/B1 (80/20)21.6 3.1 slightly tapered 15 A1/A4 (80/20) 22.0 3.8 slightly tapered 16A1/B1 (70/30) 21.0 4.1 slightly tapered 17 A1/B1 (60/40) 22.1 4.0slightly tapered Comparative Example  1 A1/B1 (60/40) 35.2 9.6 tapered 2 A1/B1 (70/30) 40.2 8.3 tapered  3 A1/B1 (60/40) 41.2 10.6 tapered

Abbreviations common in respective Tables are shown together below.

[Basic Compound]

TPI: 2,4,5-triphenylimidazole

TPSA: triphenylsulfonium acetate

HEP: N-hydroxyethylpiperidine

DIA: 2,6-diisopropylaniline

DCMA: dicyclohexylmethylamine

TPA: tripentylamine

HAP: hydroxyantipyrine

TBAH: tetrabutylammonium hydroxide

TMEA: tris(methoxyethoxyethyl)amine

PEA: N-phenyldiethanolamine

TOA: trioctylamine

DBN: 1,5-diazabicyclo[4.3.0]non-5-ene

[Surfactant]

-   W-1: Megafac F176 (produced by Dainippon Ink & Chemicals, Inc.)    (fluorine-containing)-   W-2: Megafac R08 (produced by Dainippon Ink & Chemicals, Inc.)    (fluorine- and silicon-containing)-   W-3: polysiloxane polymer KP-341 (produced by Shin-Etsu Chemical    Co., Ltd.) (silicon-containing)-   W-4: Troysol S-366 (produced by Troy Chemical)    [Solvent]    A1: propylene glycol monomethyl ether acetate    A2: 2-heptanone    A3: cyclohexanone    A4: γ-butyrolactone    B1: propylene glycol monomethyl ether    B2: ethyl lactate    [Dissolution Inhibiting Compound]    LCB: tert-butyl lithocholate

As apparent from the results in Table 1, the photosensitive compositionof the present invention is excellent in the defocus latitude dependedon line pitch, the line edge roughness and the pattern profile at theArF exposure.

[Evaluation of Immersion Exposure]

<Preparation of Resist>

The components of each of Examples 1 to 17 shown in Table 1 weredissolved in a solvent to prepare a solution having a solid contentconcentration of 8 mass %, and this solution was filtered through a0.1-μm polyethylene filter to prepare a positive resist solution. Theprepared positive resist solutions were evaluated by the followingmethods.

<Evaluation of Resolution>

An organic antireflection film ARC29A (produced by Nissan ChemicalIndustries, Ltd.) was coated on a silicon wafer and baked at 205° C. for60 seconds to form a 78-nm antireflection film. On this film, the resistcomposition prepared was coated and baked at 120° C. for 60 seconds toform a 150-nm resist film. The thus-obtained wafer was subjected totwo-beam interference exposure (wet exposure) by using pure water as theimmersion liquid. In the two-beam interference exposure (wet exposure),as shown in the FIGURE, the wafer 10 with an antireflection film and aresist film was exposed through a prism 8 and an immersion liquid (purewater) 9 by using a laser 1, a diaphragm 2, a shutter 3, threereflecting mirrors 4, 5 and 6, and a condenser lens 7. The wavelength ofthe laser 1 used was 193 nm, and a prism of forming a 65-nmline-and-space pattern 8 was used. Immediately after the exposure, theresist film was heated at 120° C. for 60 seconds, then developed with anaqueous tetramethylammonium hydroxide solution (2.38%) for 60 secondsand after rinsing with pure water, spin-dried. The obtained resistpattern was observed by a scanning electron microscope (S-9260,manufactured by Hitachi Ltd.), as a result, a 65-nm line-and-spacepattern was resolved.

The compositions of Examples 1 to 17 were found to exhibit goodimage-forming capability also in the exposure through an immersionliquid.

Examples 18 to 23 and Comparative Examples 4 to 6 (1) Formation of LowerResist Layer

FHi-028DD Resist (resist for i-line, produced by Fujifilm Olin Co.,Ltd.) was coated on a 6-inch silicon wafer by using a spin coater, Mark8, manufactured by Tokyo Electron Ltd. and then baked at 90° C. for 90seconds to obtain a uniform film having a thickness of 0.55 μm.

This film was further heated at 200° C. for 3 minutes to form a lowerresist layer having a thickness of 0.40 μm.

(2) Formation of Upper Resist Layer

The components shown in Table 2 below were dissolved in a solvent toprepare a solution having a solid content concentration of 11 mass %,and this solution was microfiltered through a membrane filter having apore size of 0.1 μm to prepare an upper resist composition.

This upper resist composition was coated on the lower resist layer inthe same manner and heated at 130° C. for 90 seconds to form an upperresist layer having a thickness of 0.20 μm.

Resins (SI-1) to (SI-5) in Table 2 are shown below.

Molecular Weight (SI-1)

15000

(SI-2)

14500

(SI-3)

 9600

(SI-4)

 8900

(SI-5)

10800

(3) Evaluation of Resist

The wafer obtained above was exposed by an ArF excimer stepper 9300(manufactured by ISI) having mounted thereon a resolving power mask,while changing the exposure amount.

Subsequently, the wafer was heated at 120° C. for 90 seconds, developedwith a tetrahydroammonium hydroxide developer (2.38 mass %) for 60seconds, rinsed with distilled water and dried to form an upper layerpattern. The defocus latitude depended on line pitch, the line edgeroughness and the pattern profile were evaluated in the same manner asin Example 1.

The results obtained are shown in Table 2.

TABLE 2 Silicon-Containing Positive Compound Surfactant (A) (g) AcidGenerator (g) Resin (10 g) Basic Compound (g) (0.03 g) Example 18 A-1(0.2) z38 (0.4) SI-1 PEA (0.02) W-2 19 A-33 (0.1) z38 (0.4) SI-2 TPA (0.025) W-4 20 A-6 (0.1) z14 (0.4) SI-1 DIA (0.02) W-3 21 A-8 (0.3) z59(0.4) SI-3 TMEA  (0.015) W-4 22 A-11 (0.2) z38 (0.4) SI-4 DIA (0.02) W-423 A-3  (0.25) z60 (0.4) SI-5 PEA (0.02) W-1 Comparative Example  4 none(—) z38 (0.4) SI-1 PEA (0.02) W-1  5 none (—) z38 (0.3) SI-1 PEA/DIA(0.01/0.01) W-4  6 none (—) z58 (0.4) SI-4 TPA (0.02) W-4 Line EdgeRoughness Solvent (ratio by mass) Defocus Latitude Depended on LinePitch (nm) (nm) Pattern Profile Example 18 A1/A3 (80/20) 22.8 3.6slightly tapered 19 A1 (100) 26.0 4.2 rectangular 20 A1/A3 (60/40) 23.53.7 slightly tapered 21 A1 (100) 25.5 4.1 rectangular 22 A1/A3 (80/20)24.4 3.9 slightly tapered 23 A1/A3 (80/20) 24.7 4.0 slightly taperedComparative Example  4 A1/A3 (80/20) 45.5 10.6 tapered  5 A1 (100) 31.58.9 tapered  6 A1/A3 (60/40) 42.3 9.1 tapered

As apparent from the results in Table 2, the photosensitive compositionof the present invention is excellent in the defocus latitude dependedon line pitch, the line edge roughness and the pattern profile also whenused as a two-layer resist.

Examples 24 to 29 and Comparative Examples 7 to 9 Preparation of Resist

The components shown in Table 3 below were dissolved in a solvent, andthe resulting solution was filtered through a 0.1-μmpolytetrafluoroethylene filter to prepare a positive resist solutionhaving a solid content concentration of 14 mass %.

<Evaluation of Resist>

The prepared positive resist solution was uniformly coated by a spincoater on a silicon substrate treated with hexamethyldisilazane, anddried under heating on a hot plate at 120° C. for 90 seconds to form aresist film having a thickness of 0.4 μm.

This resist film was exposed through a mask for a line-and-space patternby using a KrF excimer laser stepper (NA=0.63) and immediately after theexposure, heated on a hot plate at 110° C. for 90 seconds. Thereafter,the resist film was developed with an aqueous 2.38 mass %tetramethylammonium hydroxide solution at 23° C. for 60 seconds, rinsedwith pure water for 30 seconds and then dried to form a line pattern.The defocus latitude depended on line pitch, the line edge roughness andthe pattern profile were evaluated in the same manner as in Example 1.

The evaluation results are shown in Table 3.

TABLE 3 KrF, Positive Compound Surfactant (A) (g) Acid Generator (g)Resin (10 g) Basic Compound (g) (0.03 g) Example 24 A-1 (0.1) z38 (0.4)R-1 PEA (0.02) W-4 25 A-14 (0.1) z38 (0.4) R-2 PEA/DIA (0.01/0.02) W-126 A-6 (0.1) z38 (0.4) R-1 TMEA (0.02) W-4 27 A-8 (0.3) z38 (0.4) R-2PEA (0.04) W-4 28 A-11 (0.1) z59 (0.3) R-5 DIA (0.02) W-4 29 A-3  (0.33)z61 (0.4) R-2 PEA/TPA (0.01/0.02) W-3 Comparative Example  7 none (—)z38 (0.4) R-2 PEA (0.02) W-1  8 none (—) z38 (0.5) R-2 PEA (0.02) W-4  9none (—) z58 (0.4) R-1 DIA (0.02) W-4 Line Edge Roughness Solvent (ratioby mass) Defocus Latitude Depended on Line Pitch (nm) (nm) PatternProfile Example 24 A1/B1 (60/40) 27.4 4.4 slightly tapered 25 A1/B1(60/40) 28.0 4.5 rectangular 26 A1/A4 (80/20) 28.5 4.6 slightly tapered27 A1/B1 (60/40) 23.3 3.7 rectangular 28 A1/B1 (60/40) 28.9 4.6 slightlytapered 29 A1/B1 (60/40) 26.0 4.2 slightly tapered Comparative Example 7 A1/B1 (60/40) 39.9 7.7 tapered  8 A1/B1 (80/20) 36.2 9.6 tapered  9A1/A3 (60/40) 40.5 8.6 tapered

The weight average molecular weight and dispersity of each of Resins(R-1) to (R-5) used in Table 3 are shown in Table 4 below.

TABLE 4 Weight Average Dispersity Resin Molecular Weight (Mw/Mn) R-113000 1.2 R-2 11000 1.7 R-3 13000 1.2 R-4 10000 1.8 R-5 11000 1.8

As apparent from the results in Table 3, the photosensitive compositionof the present invention is excellent in the defocus latitude dependedon line pitch, the line edge roughness and the pattern profile also as apositive resist composition for exposure with a KrF excimer laser.

Examples 30 to 35 and Comparative Examples 10 to 12 Preparation ofResist

The components shown in Table 5 below were dissolved in a solvent, andthe resulting solution was filtered through a 0.1-μmpolytetrafluoroethylene filter to prepare a negative resist solutionhaving a solid content concentration of 14 mass %.

The prepared negative resist solutions were evaluated in the same manneras in Example 24. The results obtained are shown in Table 5.

TABLE 5 KrF, Negative Compound Surfactant (A) (g) Acid Generator (g)Resin (10 g) Basic Compound (g) (0.03 g) Example 30 A-1 (0.1) z38 (0.4)P-1 PEA (0.02) W-4 31 A-33 (0.1) z14 (0.5) P-3 PEA/DIA (0.01/0.02) W-432 A-6 (0.1) z38 (0.4) P-3 DIA (0.02) W-1 33 A-8 (0.3) z38 (0.3) P-2 PIA(0.01/0.02) W-4 34 A-11 (0.1) z59 (0.3) P-2 PEA/DIA (0.03/0.01) W-4 35A-3 (0.1) z61 (0.5) P-1 PEA (0.02) W-3 Comparative Example 10 none (—)z38 (0.4) P-1 HAP (0.02) W-1 11 none (—) z38 (0.5) P-3 DIA (0.02) W-4 12none (—) z58  (0.45) P-2 PEA (0.02) W-4 Defocus Latitude CrosslinkingAgent Depended on Line Pitch Line Edge Roughness Solvent (ratio by mass)(g) (nm) (nm) Pattern Profile Example 30 A1/B1 (60/40) CL-1 (3) 24.1 3.8slightly tapered 31 A1/B1 (80/20) CL-2 (2) 25.0 4.0 rectangular 32 A1/B1(60/40) CL-3 (2) 29.1 3.8 slightly tapered 33 A1/B1 (60/40) CL-4 (3)25.3 4.0 rectangular 34 A1/A4 (80/20) CL-5 (2) 29.3 3.6 slightly tapered35 A1/B1 (60/40) CL-6 (2) 24.8 4.0 slightly tapered Comparative Example10 A1/B1 (60/40) CL-1 (3) 40.1 8.8 tapered 11 A1/B1 (70/30) CL-2 (2)35.6 7.6 tapered 12 A1/A3 (90/10) CL-3 (2) 29.8 9.0 tapered

The structure, molecular weight and molecular weight distribution ofeach alkali-soluble resin and the crosslinking agents in Table 5 areshown below.

Mw Mw/Mn P-1

16000 2.30 P-2

12000 1.2 P-3

 6000 1.2

As apparent from the results in Table 5, the photosensitive compositionof the present invention is excellent in the defocus latitude dependedon line pitch, the line edge roughness and the pattern profile also as anegative resist composition for exposure with a KrF excimer laser.

Examples 36 to 41 and Comparative Examples 13 to 15 Preparation ofResist

The components shown in Table 3 were dissolved in a solvent, and theresulting solution was filtered through a 0.1-μm polytetrafluoroethylenefilter to prepare a positive resist solution having a solid contentconcentration of 12 mass %.

<Evaluation of Resist>

The prepared positive resist solution was uniformly coated by a spincoater on a silicon substrate treated with hexamethyldisilazane, anddried under heating on a hot plate at 120° C. for 60 seconds to form aresist film having a thickness of 0.3 μm.

This resist film was irradiated by an electron beam projectionlithography apparatus manufactured by Nikon Corp. (accelerating voltage:100 KeV) and immediately after the irradiation, heated on a hot plate at110° C. for 90 seconds. Furthermore, the resist film was developed withan aqueous tetramethylammonium hydroxide solution having a concentrationof 2.38 mass % at 23° C. for 60 seconds, rinsed with pure water for 30seconds and then dried to form a line-and-space pattern. The defocuslatitude depended on line pitch, the line edge roughness and the patternprofile were evaluated in the same manner as in Example 1.

The evaluation results are shown in Table 6.

TABLE 6 EB, positive Defocus Latitude Depended on Line Edge Line Pitch(nm) Roughness (nm) Pattern Profile Example 36 23.9 3.8 slightly tapered37 24.8 3.0 rectangular 38 28.9 3.7 slightly tapered 39 29.1 3.3rectangular 40 24.8 3.9 slightly tapered 41 26.7 3.3 slightly taperedComparative Example 13 40.8 10.1 tapered 14 40.1 10.0 tapered 15 38.29.1 tapered

As apparent from the results in Table 6, the photosensitive compositionof the present invention is excellent in the defocus latitude dependedon line pitch, the line edge roughness and the pattern profile also as apositive resist composition for electron beam irradiation.

Examples 42 to 47 and Comparative Examples 16 to 18 Preparation ofResist

The components shown in Table 5 were dissolved in a solvent, and theresulting solution was filtered through a 0.1-μm polytetrafluoroethylenefilter to prepare a negative resist solution having a solid contentconcentration of 12 mass %.

<Evaluation of Resist>

The prepared negative resist solution was uniformly coated by a spincoater on a silicon substrate treated with hexamethyldisilazane, anddried under heating on a hot plate at 120° C. for 60 seconds to form aresist film having a thickness of 0.3 nm.

This resist film was irradiated by an electron beam projectionlithography apparatus manufactured by Nikon Corp. (accelerating voltage:100 KeV) and immediately after the irradiation, heated on a hot plate at110° C. for 90 seconds. Furthermore, the resist film was developed withan aqueous tetramethylammonium hydroxide solution having a concentrationof 2.38 mass % at 23° C. for 60 seconds, rinsed with pure water for 30seconds and then dried to form a line-and-space pattern. The defocuslatitude depended on line pitch, the line edge roughness and the patternprofile were evaluated in the same manner as in Example 1.

The evaluation results are shown in Table 7.

TABLE 7 EB, negative Defocus Latitude Depended on Line Edge Line Pitch(nm) Roughness (nm) Pattern Profile 42 22.8 3.6 slightly tapered 43 27.43.4 rectangular 44 25.6 4.5 slightly tapered 45 24.1 3.8 rectangular 4623.9 4.2 slightly tapered 47 25.5 3.9 slightly tapered ComparativeExample 16 36.3 10.9 tapered 17 33.3 10.3 tapered 18 36.7 10.6 tapered

As apparent from the results in Table 7, the photosensitive compositionof the present invention is excellent in the defocus latitude dependedon line pitch, the line edge roughness and the pattern profile also as anegative resist composition for electron beam irradiation.

Examples 48 to 53 and Comparative Examples 19 to 21 Preparation ofResist

The components shown in Table 3 were dissolved in a solvent, and theresulting solution was filtered through a 0.1-μm polytetrafluoroethylenefilter to prepare a positive resist solution having a solid contentconcentration of 8 mass %.

<Evaluation of Resist>

The prepared positive resist solution was uniformly coated by a spincoater on a silicon substrate treated with hexamethyldisilazane, anddried under heating on a hot plate at 120° C. for 60 seconds to form aresist film having a thickness of 0.15 μm. The obtained resist film wassubjected to surface exposure with EUV light (wavelength: 13 nm) whilechanging the exposure amount in 0.5-mJ steps in the range from 0 to 10.0mJ and baked at 110° C. for 90 seconds. Thereafter, the dissolution rateat each exposure amount was measured by using an aqueous 2.38%tetramethylammonium hydroxide (TMAH) solution, and a sensitivity curvewas obtained from the measured values. The sensitivity was defined asthe exposure amount when the dissolution rate of resist was saturated onthis sensitivity curve. Also, the dissolution contrast (γ value) wascalculated from the gradient in the straight line part of thesensitivity curve. As the γ value is larger, the dissolution contrast isbetter.

The evaluation results are shown in Table 8 below.

TABLE 8 EUV Sensitivity (mJ/cm²) γ Value Example 48 2.2 15.9 49 2.6 16.150 2.1 14.9 51 1.8 15.2 52 2 16.9 53 2.3 15.5 Comparative Example 19 4.56.9 20 5.0 7.3 21 5.6 6.8

As apparent from the results in Table 8, the resist composition of thepresent invention is excellent in terms of high sensitivity and highcontract in the characteristic evaluation by the irradiation of EUVlight as compared with the compositions of Comparative Examples.

According to the present invention, a photosensitive composition assuredof small line edge roughness, good pattern profile and low defocuslatitude depended on line pitch and improved in the sensitivity anddissolution contrast at the exposure with EUV light, a compound for usein the photosensitive composition, and a pattern forming method usingthe photosensitive composition can be provided.

The entire disclosure of each and every foreign patent application fromwhich the benefit of foreign priority has been claimed in the presentapplication is incorporated herein by reference, as if fully set forth.

What is claimed is:
 1. A photosensitive composition comprising: (A) acompound capable of generating a compound represented by formula (I)upon irradiation with actinic rays or radiation:

wherein R₁ and R₂ each independently represents a monovalent organicgroup, provided that at least either one of R₁ and R₂ has a protonacceptor functional group, R₁ and R₂ may combine to form a ring and thering formed may have a proton acceptor functional group; and X₁ and X₂each independently represents —CO— or —SO₂—, said compound (A) being asulfonium salt compound of the compound represented by formula (I) or aniodonium salt compound of the compound represented by formula (I); (B) acompound capable of generating an acid upon irradiation with actinicrays or radiation; and (C) a resin capable of decomposing under anaction of an acid to increase the solubility of the resin (C) in analkali developer, wherein: the proton acceptor functional group has apartial structure selected from the group consisting of a crown etherstructure, an aza-crown ether structure, a tertiary amine structure, asecondary amine structure, a primary amine structure, a pyridinestructure, an imidazole structure, a pyrazine structure and an anilinestructure; when the proton acceptor functional group contains a tertiaryamine, a secondary amine, or a primary amine, as a partial structure, acarbon atom connected to a nitrogen atom in the tertiary amine, thesecondary amine, or the primary amine connects only to one or morehydrogen, carbon, and/or oxygen atoms; the resin (C) has no aromaticgroup; and the compound (A) capable of generating a compound representedby formula (I) upon irradiation with actinic rays or radiation is acompound represented by the following formula (A1) or (A2):

wherein R₂₀₁, R₂₀₂ and R₂₀₃ each independently represents an organicgroup, provided that when two members out of R₂₀₁ to R₂₀₃ are both analkylene group, the two alkylene groups may combine to form a ringstructure, and the ring may contain an oxygen atom, a sulfur atom, anester bond, an amide bond or a carbonyl group; X represents an anion ofthe compound represented by formula (I); and R₂₀₄ and R₂₀₅ eachindependently represents an aryl group, an alkyl group or a cycloalkylgroup.
 2. The photosensitive composition according to claim 1, whereinthe compound represented by formula (I) is represented by formula (II):

wherein R₁ and R₃ each independently represents a monovalent organicgroup, provided that at least either one of R₁ and R₃ has a protonacceptor functional group, R₁ and R₃ may combine to form a ring and thering formed may have a proton acceptor functional group; X₁, X₂ and X₃each independently represents —CO— or —SO₂—; A represents a divalentlinking group; B represents a single bond, an oxygen atom or —N(Rx)-; Rxrepresents a hydrogen atom or a monovalent organic group; when B is—N(Rx)-, R₃ and Rx may combine to form a ring; and n represents 0 or 1.3. A pattern forming method comprising: forming a photosensitive filmfrom a photosensitive composition according to claim 1; and exposing anddeveloping the photosensitive film.
 4. The photosensitive compositionaccording to claim 1, wherein the compound as the component (B) is asulfonium salt of fluoro-substituted alkanesulfonic acid,fluorine-substituted benzenesulfonic acid or fluorine-substituted imideacid.
 5. The photosensitive composition according to claim 1, whereinthe resin as the component (C) has a repeating unit having a lactonegroup.
 6. The photosensitive composition according to claim 1, whereinR₁ and R₂ combine to form a ring and the ring formed has a protonacceptor functional group, and the ring formed includes a structurewhere the organic groups of R₁ and R₂ are further bonded through analkylene group, an oxy group or an imino group.
 7. The photosensitivecomposition according to claim 1, wherein at least either one of X₁ andX₂ is —SO₂—.
 8. The photosensitive composition according to claim 2,wherein the divalent linking group as A is a divalent linking grouphaving a carbon number of 1 to 8 and containing a fluorine atom.
 9. Thephotosensitive composition according to claim 2, wherein X₁, X₂ and X₃each is —SO₂—.
 10. The photosensitive composition according to claim 1,wherein the resin (C) contains a repeating unit having an alicyclichydrocarbon-containing partial structure represented by formulae (pI):

wherein in formulae (pI), R₁₁ represents a methyl group, an ethyl group,an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup or a sec-butyl group; and Z represents an atomic group necessaryfor forming a monocyclic cycloalkyl group together with the carbon atom.11. The photosensitive composition according to claim 1, which furthercomprises: a solvent having at least one ketone structure.
 12. Thephotosensitive composition according to claim 1, wherein the protonacceptor functional group contains a non-cyclic tertiary amine as apartial structure.
 13. The photosensitive composition according to claim1, wherein the proton acceptor functional group contains at least oneselected from the group consisting of a pyrrolidine structure, apiperidine structure, a piperazine structure, a pyridine structure, animidazole structure, a pyrazine structure, and an aniline structure. 14.The photosensitive composition according to claim 1, wherein the protonacceptor functional group contains a primary amine as a partialstructure.
 15. The photosensitive composition according to claim 1,wherein the proton acceptor functional group contains a secondary amineas a partial structure.